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ever changing but constant
soothing but wild
comforting but scary
the noise of the ever crashing waves
the shapes, and land formed by water

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LIFE AND TRADE:

Its the biggest highway on earth connecting everything land mass and island. Its also whete ww believed the life to have started and along with that something that is most vital in maintaining life on earth with heat transferring currents and the water for rain and monsoons in various parta on this planet. Also it is the economic corridor through which the world trade moves , the lifeline of world commerce as it has been for  ages and throughout the various civilisations.

Tejinder Singh

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I'd rather spend life under water and come to the surface at times.  The picture is me diving on a shipwreck.  It amazes me that the Bahamas and Cuba were once one giant island the size of Florida and the ocean we dive there now was once dry land.  Seeing the earth's surface as both land and submerged land changed my entire perspective on the concept of shorelines, islands and continents.  I look forward to learning more about where we all came from.
Leo

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Samantha fell
To me the ocean is an intimidating expanse of space full of wonders that are beyond anything I could imagine!

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The ocean...70% of it cover our earth's sufaces and yet less than 5% of it have been exlpored, that means 95% of the ocean still remains untouched. And I think think picture fits really well with adventure because the ocean provides so many adventures and diving into it you always find something or come back up with a story.
MR

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70% of our earth surface consists of oceans and most of it still remains a mystery before us. I have always been fascinated by the oceans and I look forward to learn more about the life, physical properties and beauty of the ocean.
Nazreen

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The oceans are one of, if not the most important part of our planet. They are so rich in life and wonder. Yet we have so much to learn about them.

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Something so powerful yet need our protection - or rather respect

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I chose this imagen because i think the ocean keeps a beautiful life in there, i love dolphins and every living thing on it, i also worried the pollution and destruction that we are responsables so I would like to raise awareness to save our oceans from ourselves.

Edson Hernandez

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Chemistry is a big part of how not only our bodies function but how our oceans do too.

I am intrigued to discover how elements in the ocean coincide and allow the ecosystem to function as it does, and possibly how this can be impacted by humans.

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Magic and fantastic place. Love diving, swimming, looking at whales.

Liza

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Oceans are the vast water bodies having numerous kinds of species from microscopic algae to giant blue whale. Ocean, in one hand providing habitat, food and in other hand it balance the ecosystem and diversity.
----- Shamima Sultana

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I have just graduated with a BSc in Marine Biology from UCT in South Africa. My passion is rooted in the ocean's beauty, complexity and wonder, however, my willingness to continue in this career path is based on my love for how it connects all of us and how important it should be to all of us to protect it. Although I also studied and am fascinated by physical oceanography, I have always been drawn to the conservation of the living things residing in the ocean. - Shantelle Smith

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I love Dolphins.
They help rescue othe species.

Hsu Wai Wai Tun

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Ocean is a greatest secret for humanity, greatest source of sustainable energy, greatest   oxygen creature, greatest hope for our future... I can continue this list, but it is so inspiring that it is better to stay calm and to think about peaceful wind of change in our life that is strongly related to the ocean.
Dmytro

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I am fascinated by these tiny creatures
Fiona

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i love oceans

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This is a photo of one of my kids, having the craic at a sea pool, part of a cluster of sea pools, known as the Pollock Holes, in the west of Ireland. He doesn't swim so much these days, as he's grown up, however, I've swapped places with him and s
pend my free time open water swimming. I'm immersed in the sea and know virtually nothing of this environment, so, I want to know what it is I am swimming in and - how I can help to conserve it. (Anna Maria)

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The oceans are such an incredible place and there is still such little we know about them. A common intertidal organism is the chiton, an understudied mollusc with some interesting features and beautiful colours. If there's so little we know about these common and easily accessible creatures then I can only imagine how much there is for us to discover about the rest of the oceans.
Chloe Brown

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The ocean is very powerful and sometimes terrifying. The ocean always makes me feel paceful and calm. I deeply am triggered by the oceans and  would love to learn more about them
Juliette

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There is so much more to discover about the deep ocean, and to be around people currently doing that exact thing is fascinating.
Anna

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in its contributions to the sustainability of life on earth. The ocean contains vast amounts of biodiversity that require awareness and conservation efforts by all stakeholders. I have selected a leatherback sea turtle (Dermochelys coriacea) as they are modern-day dinosaurs of the sea with not much knowledge (yet) on the male turtles.

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For a part of our planet so vast and so vital when it comes to sustaining entire species both in the water and on dry land, the ignorance of the ocean's fragility is bewildering. To me, the oceans are a never ending source of curiosity and interest before mentioning the complexity and beauty that is hidden under the waves. However, very quickly this idea is shadowed by the destruction taking place on a worldwide scale from the depths of the ocean trenches to the shallow coral reefs leading to a very distorted image/perception of the marine ecosystem forming. This is represented in the image as a stark contrast between a pioneering marine animal (turtle) and utter devastiation caused by humans (wide scale bleaching of corals).

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Oceans are amazing places and cover about 70% of the planet and there are 7 oceans. I am doing this course because I love whales and want to learn more about how many of the creatures that live in oceans survive the rubbish and chemicals  that we put into the oceans each year.
Gina Kendall

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The giant isopod image of this course made me remember similar looking horseshoe crabs. Some years ago I was teaching English in China when I was invited out to dinner. My local friend suggested horseshoe crab. They are sold openly and everywhere in the city of Zhanjiang, Guangdong. I thought it might be nice to try for a first time, and because they are sold from fish tanks everywhere it never even occurred to me they are rare. But while we were waiting my friend mentioned that there is an international convention protecting horseshoe crabs. I felt so bad about it... I should've known. It was too late to stop the order but could only manage a mouthful, from guilt. My Chinese friend ate the rest. Horseshoe crabs are amazing, prehistoric creatures. I still feel guilty about ordering one. Better knowledge of the oceans can help us protect oceanic environments in so many ways.

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Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to arachnids such as spiders, ticks, and scorpions.

Horseshoe crabs live primarily in and around shallow coastal waters on soft, sandy or muddy bottoms. They are generally found in the intertidal zone at spring high tides. They are eaten in some parts of Asia, and used as fishing bait, in fertilizer and in science (especially Limulus amebocyte lysate, which is used for the detection and quantification of bacterial endotoxins). In recent years, population declines have occurred as a consequence of coastal habitat destruction and overharvesting. Tetrodotoxin may be present in one horseshoe crab species, Carcinoscorpius rotundicauda.

The fossil record of Xiphosura goes back over 440 million years to the Ordovician period, with the oldest representatives of the modern family Limulidae dating to approximately 250 million years ago during the Early Triassic. As such, the extant forms have been described as " living fossils". The last common ancestor of the four present species is estimated to have lived about 135 million years ago in the Cretaceous. Some molecular analyses have placed Xiphosura within Arachnida, with a 2019 molecular analysis placing them as the sister group of Ricinulei.

The family name Limulidae comes from the genus Limulus, from the word limulus in Latin meaning "askance", or "a little askew".

Horseshoe crabs resemble crustaceans but belong to a separate subphylum of the arthropods, Chelicerata. Horseshoe crabs are closely related to the extinct eurypterids (sea scorpions), which include some of the largest arthropods to have ever existed, and the two may be sister groups. Other studies have placed eurypterids closer to the arachnids in a group called Merostomata. The enigmatic Chasmataspidids are also thought to be closely related to the horseshoe crabs. The earliest horseshoe crab fossils are found in strata from the Lower Ordovician period, roughly 480 million years ago.

The Limulidae are the only recent family of the order Xiphosura, and contains all four living species of horseshoe crabs:

Carcinoscorpius rotundicauda, the mangrove horseshoe crab, found in South and Southeast Asia

Limulus polyphemus, the Atlantic or American horseshoe crab, found along the Atlantic coast of the United States and the Southeast Gulf of Mexico

Tachypleus gigas, the Indo-Pacific, Indonesian, Indian or southern horseshoe crab, found in South and Southeast Asia

Tachypleus tridentatus, the Chinese, Japanese or tri-spine horseshoe crab, found in Southeast and East Asia

After Bicknell et al. 2021 and Lamsdell et al. 2020

Incertae sedis

†Albalimulus? Bicknell & Pates, 2019 Ballagan Formation, Scotland, Early Carboniferous (Tournaisian) (Considered Xiphosura incertae sedis by Lamsdell, 2020)

†Casterolimulus Holland, Erickson & O'Brien, 1975 Late Cretaceous (Maastrichtian) Fox Hills Formation, North Dakota, USA (Inconsistently placed in this family)

†Heterolimulus gadeai Vıa & Villalta, 1966 Alcover Limestone Formation, Spain, Middle Triassic (Ladinian)

†Limulitella Størmer, 1952 Middle-Upper Triassic, France, Germany, Tunisia, Russia

†Sloveniolimulus Bicknell et al., 2019 Strelovec Formation, Slovenia Middle Triassic (Anisian)

†Tarracolimulus Romero & Vıa Boada, 1977 Alcover Limestone Formation, Spain, Middle Triassic (Ladinian)

†Victalimulus Riek & Gill, 1971 Lower Cretaceous (Aptian) Korumburra Group, NSW, Australia

†Yunnanolimulus Zhang et al., 2009 Middle Triassic (Anisian), Guanling Formation, Yunnan, China

†Mesolimulus Middle Triassic-Late Cretaceous England, Spain, Siberia, Germany, Morocco

†Ostenolimulus Lamsdell et al. 2021 Early Jurassic (Sinemurian) Moltrasio Limestone, Italy

†Volanalimulus Lamsdell, 2020 Early Triassic, Madagascar.

Subfamily Limulinae Leach, 1819

Subfamily Tachypleinae Pocock, 1902

Cladogram after Lasmdell 2020.

Underside of two horseshoe crabs showing the legs and book gills

The entire body of the horseshoe crab is protected by a carapace, which like the rest of the exoskeleton is unmineralized. It has two compound lateral eyes, each composed of about 1,000 ommatidia, plus a pair of median eyes that are able to detect both visible light and ultraviolet light, a single parietal eye, and a pair of rudimentary lateral eyes on the top. The latter becomes functional just before the embryo hatches. Also, a pair of ventral eyes is located near the mouth, as well as a cluster of photoreceptors on the telson. Having relatively poor eyesight, the animals have the largest rods and cones of any known animal, about 100 times the size of humans, and their eyes are a million times more sensitive to light at night than during the day.

They use their chelicerae-a pair of small appendages-for moving food into the mouth. The next five pairs of appendages, the first of which are the pedipalps, are used for locomotion (ambulatory legs). The mouth is located in the center of the legs, whose bases are referred to as gnathobases, and have the same function as jaws and help grind up food. In extant species and other fossil xiphosurans (e.g. ) their appendages are uniramous, but in other related non-xiphosurid euchelicerates such as and Dibasterium the appendages are biramous. The pedipalps on a male change shape on their terminal molt, becoming boxing glove-like claspers that are used for grasping the female during mating. The last pair of legs for both males and females are the main legs used for pushing when walking on the ocean floor. The remaining leg pairs have a weak claw at the tip. Lost legs or the telson (tail) may slowly regenerate, and cracks in the body shell can heal.

Behind its legs, the horseshoe crab has book gills, which exchange respiratory gases, and are also occasionally used for swimming. As in other arthropods, a true endoskeleton is absent, but the body does have an endoskeletal structure made up of cartilaginous plates that support the book gills.

Females are about 20-30% larger than males. The smallest species is C. rotundicauda and the largest is T. tridentatus. On average, males of C. rotundicauda are about 30 centimetres (12 inches) long, including a tail ( telson) that is about 15 cm (6 in), and their carapace ( prosoma) is about 15 cm (6 in) wide. Some southern populations (in the Yucatán Peninsula) of L. polyphemus are somewhat smaller, but otherwise this species is larger.

In the largest species, T. tridentatus, females can reach as much as 79.5 cm ( in) long, including their tail, and up to 4 kg (9 lb) in weight. This is only about 10-20 cm (4-8 in) longer than the largest females of L. polyphemus and T. gigas, but roughly twice the weight.

The juveniles grow about 33% larger with every molt until reaching adult size. Atlantic horseshoe crabs molt in late July.

Horseshoe crabs are more often found on the ocean floor searching for worms and molluscs, which are their main food. They may also feed on crustaceans and even small fish. Foraging usually takes place at night. Gravel and sand particles are ingested to further grind up food in a gizzard before passing it into the stomach.

Horseshoe crabs mating

Horseshoe crab eggs

During the breeding season (spring and summer in the Northeast U.S.; year-round in warmer locations or when the full moon rises), horseshoe crabs migrate to shallow coastal waters. The smaller male horseshoe crab clings to the back or opisthosoma of the larger female using specialized front claws and fertilizes the eggs as they are laid in the sand. Additional males called "satellite males" which are not attached to the female may surround the pair and have some success in fertilizing eggs. Young female horseshoe crabs can be identified by the lack of mating scars.

The female can lay between 60,000 and 120,000 eggs in batches of a few thousand at a time. The eggs may be inseminated within 20 to 30 minutes. In L. polyphemus, the eggs take about two weeks to hatch; shore birds eat many of them before they hatch. The larvae molt six times during the first year and annually after the first 3 or 4 years.

Natural breeding of horseshoe crabs in captivity has proven to be difficult. Some evidence indicates that mating takes place only in the presence of the sand or mud in which the horseshoe crab's eggs were hatched; it is not known with certainty what is in the sand that the crabs can sense or how they sense it. Artificial insemination and induced spawning have been done on a relatively large scale in captivity, and eggs and juveniles collected from the wild are often raised to adulthood in captivity.

In order to preserve and ensure the continuous supply of the horseshoe crab, a breeding centre was built in Johor, Malaysia where the crabs are bred and released back into the ocean in thousands once every two years. It is estimated to take around 12 years before they are suitable for consumption.

Horseshoe crabs use hemocyanin to carry oxygen through their blood. Their blood contains amebocytes, which play a similar role to the white blood cells of vertebrates in defending the organism against pathogens. Amebocytes from the blood of L. polyphemus are used to make Limulus amebocyte lysate (LAL), which is used for the detection of bacterial endotoxins in medical applications. There is a high demand for the blood, the harvest of which involves collecting and bleeding the animals, and then releasing them back into the sea. Most of the animals survive the process; mortality is correlated with both the amount of blood extracted from an individual animal, and the stress experienced during handling and transportation. Estimates of mortality rates following blood harvesting vary from 3-15% to 10-30%. Approximately 500,000 Limulus are harvested annually for this purpose. Declining horseshoe crab populations on the East Coast of the United States endanger certain bird species which feed upon their eggs.

Bleeding may also prevent female horseshoe crabs from being able to spawn or decrease the number of eggs they are able to lay. Up to 30% of an individual's blood is removed, according to the biomedical industry, although NPR reported that it "can deplete them of more than half their volume of blue blood." The horseshoe crabs spend between one and three days away from the ocean before being returned. As long as the gills stay moist, they can survive on land for four days. Some scientists are skeptical that certain companies return their horseshoe crabs to the ocean at all, instead suspecting them of selling the horseshoe crabs as fishing bait.

The harvesting of horseshoe crab blood in the pharmaceutical industry is in decline. In 1986, Kyushu University researchers discovered that the same test could be achieved by using isolated Limulus clotting factor C (rFC), an enzyme found in LAL, as by using LAL itself. Jeak Ling Ding, a National University of Singapore researcher, patented a process for manufacturing rFC; on 8 May 2003, synthetic isolated rFC made via her patented process became available for the first time. Industry at first took little interest in the new product, however, as it was patent-encumbered, not yet approved by regulators, and sold by a single manufacturer, Lonza Group. In 2013, however, Hyglos GmbH also began manufacturing its own rFC product. This, combined with the acceptance of rFC by European regulators, the comparable cost between LAL and rFC, and support from Eli Lilly and Company, which has committed to use rFC in lieu of LAL, is projected to all but end the practice of blood harvesting from horseshoe crabs.

In December 2019, a report of the US Senate which encouraged the Food and Drug Administration to "establish processes for evaluating alternative pyrogenicity tests and report back [to the Senate] on steps taken to increase their use" was released; PETA backed the report.

In June 2020, it was reported that U.S. Pharmacopeia had declined to give rFC equal standing with horseshoe crab blood. Without the approval for the classification as an industry standard testing material, U.S. companies will have to overcome the scrutiny of showing that rFC is safe and effective for their desired uses, which may serve as a deterrent for usage of the horseshoe crab blood substitute.

Vaccine research and development during the COVID-19 pandemic has added additional "strain on the American horseshoe crab."

In 2023, the U.S. Fish and Wildlife Service halted the harvesting of horseshoe crabs in the Cape Romain National Wildlife Refuge, South Carolina, from March 15 to July 15 to aid their reproduction. This decision was influenced by the importance of horseshoe crab eggs as a food source for migratory birds and the ongoing use of horseshoe crabs for bait and their blood in medical products. The ban supports the conservation goals of the refuge, spanning 66,000 acres (26,700 hectares) of marshes, beaches, and islands near Charleston.

Horseshoe crabs are used as bait to fish for eels (mostly in the United States) and whelk, or conch. Nearly 1 million (1,000,000) crabs a year are harvested for bait in the United States, dwarfing the biomedical mortality. However, fishing with horseshoe crab was banned indefinitely in New Jersey in 2008 with a moratorium on harvesting to protect the red knot, a shorebird which eats the crab's eggs. A moratorium was restricted to male crabs in Delaware, and a permanent moratorium is in effect in South Carolina. The eggs are eaten in parts of Southeast Asia, Johor and China.

A low horseshoe crab population in the Delaware Bay is hypothesized to endanger the future of the red knot. Red knots, long-distance migratory shorebirds, feed on the protein-rich eggs during their stopovers on the beaches of New Jersey and Delaware. An effort is ongoing to develop adaptive-management plans to regulate horseshoe crab harvests in the bay in a way that protects migrating shorebirds.

The population of T. gigas in Indonesia and Malaysia has decreased dramatically in the past decade.[when? ] The harvesting of T. gigas is largely used to supply Thailand with primarily female T. gigas, which is considered a local delicacy. This female harvesting has led to an unbalanced sex ratio in the wild, which also contributes to its declining population in the area.

Horseshoe crabs are the sister group to ricinuleids, and are within the family Arachnida, classifying them as aquatic arachnids. Their aquatic nature is the result of a secondary shift to marine life, following the initial shift to land by the common ancestor of all arachnids.

The radiation of horseshoe crabs occurred rapidly and resulted in 88 total lineages, of which only 4 remain. The Atlantic species is sister to the three Asian species, the latter of which are likely the result of two divergences relatively close in time.

Now-extinct horseshoe crabs traveled to land at least five times throughout history, two of which resulted in the formation of a major clade. These clades, Belinurina and Austrolimulidae both inhabited marginally marine environments, such as swamps and rivers, which are both distinct from the habitats of the extant species, which did not undergo the same transition to land.

As generalists, horseshoe crabs can have a broad diet and live in diverse habitats, meaning they are more likely to survive and produce viable offspring in more places. Horseshoe crabs also have an incredibly efficient immune system, and can also be successful in areas with high concentrations of bacteria. Amoebocytes in the bloodstream attack bacterial cells, and in doing so act as coagulants around the foreign body, preventing them from multiplying. This trait is an adaptation to their often bacteria-rich environment. Their ability to succeed in many environments limits selective forces, as there are few, if any, mutations that would result in a more beneficial allele that would make horseshoe crabs more suited for survival.

In the Atlantic horseshoe crab, microRNA's exist on 7 loci, comparatively high to the 2 loci in spiders and scorpions, meaning horseshoe crabs have comparatively high rates of gene regulation, which could contribute to their morphological status. Additionally, several other gene clusters are present in at least 6, and often 7 loci.

The common ancestor to Arachnids underwent a whole genome duplication event, which was likely followed by another duplication event in the common ancestor to the 4 extant species of horseshoe crabs about 135 million years ago, and evidence points to two additional events having occurred since then. However, many of these ancient genes have likely undergone either neo-functionalization or sub-functionalization as a result of functional divergence, meaning their expression is not the same as it was following the WGD event, as seen in other chelicerate lineages.

Evidence from genomic sequencing

The genome assembly of two species of horseshoe crabs, C. rotundicauda and T. tridentatus, suggests a genome size of 1.72 Gb for both species. The relatively large size of these genomes is believed to be another result of multiple rounds of whole genome duplication. In C. rotundicauda, the number of Hox genes is 43, which mainly exist on five Hox clusters. There are 36 hox genes on 3 clusters in T. tridentatus. Both species contain two clusters. The L. polyphemus similarly contains 4 hox clusters. The evidence of at least 3 hox clusters in these three species indicates at least two rounds of whole genome duplication.

Homeobox genes are present in more than four copies. Furthermore, most chromosomes in C. rotinducauda exhibit synteny with between 4 and 8 chromosomes, also indicating that at least two, and likely 3 rounds of whole genome duplication occurred in the common ancestor of the 4 extant species between 135 and 500 million years ago.

Many of the ancient genes present due to past whole genome duplication events have experienced ongoing mutations, and as a result, have become pseudogenes, and lost their ability to code for proteins. Evidence for this phenomenon was found in a population of C. Rotundica in Hong Kong, in which 9/10 individuals sequenced exhibited deletion of the paralog of the Unpg-A1 gene, indicating an ongoing mutative process of pseudogenization in C. rotundicauda.

Several hypotheses have been proposed as possible mechanisms for the size difference between male and female horseshoe crabs. The sexual size dimorphism of horseshoe crabs that results in a larger average size in females than males is likely a result of the amalgamation of many different aspects of these hypotheses and more:

Horseshoe crabs exhibit self-similar size preferences when choosing a mate. Inverse relationships in which the male is larger than the female are rare. The maintenance of size difference in mating partners is likely in part a result of the stability of this self-similar preference and dimorphism.

Mature females undergo an additional year of maturation and an additional molt to males, a contributing factor in their larger average size to mature males.

Larger female horseshoe crabs can house more eggs within their bodies, and therefore pass on more genetic material than smaller females during each mating cycle.

Satellite males found occupying the ideal mating position were found to be on average in better condition than those in other mating positions, indicating a significant relationship between reproductive success and the male's condition, as satellite males account for nearly 40% of fertilization.

There is no evidence of assortative mating, indicating sexual selection is likely not the main factor in this sexual size dimorphism. Rather than favoring size, selection favors the ability to switch to satellite behavior, as individuals like these can contribute more genetic material to the next population, which will increase the number of individuals with the ability to engage in both types of mating behaviors.

Development along shorelines is dangerous to horseshoe crab spawning, limiting available space and degrading habitat. Bulkheads can block access to intertidal spawning regions as well.

Because of the destruction of habitat and shoreline development, use in fishing, plastic pollution, status as a culinary delicacy in some areas, and use for scientific research and advancements, the horseshoe crab is facing down endangered and extinct statuses. One species, T. tridentatus, has already been declared extirpated from Taiwan. Facing a greater than 90% population decrease in T. tridentatus juveniles, it is suspected that Hong Kong will be the next to declare the horseshoe crab extirpated from its area. The species is listed as endangered on the IUCN Red List, specifically because of overexploitation and loss of critical habitat leading to a steep decline in population size.

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^ On Paleolimulus from the Mazon Creek Konservat-Lagerstätte

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^ Briggs, D. E.; Siveter, D. J.; Siveter, D. J.; Sutton, M. D.; Garwood, R. J.; Legg, D. (2012). "Silurian horseshoe crab illuminates the evolution of arthropod limbs". Proceedings of the National Academy of Sciences of the United States of America. 109 (39): 15702-15705. Bibcode:2012PNAS..10915702B. doi:10.1073/pnas.1205875109. PMC . PMID 22967511.

^ Castillo Y, Garabedian LA (26 April 2007). Limb Regeneration in Horseshoe Crabs (PDF) (B.S. thesis). Worcester Polytechnical Institute. Archived from the original (PDF) on 17 January 2023.

Manton SM (1977) ^ The Arthropoda: habits, functional morphology, and evolution Archived 2023-04-05 at the Wayback Machine Page 57, Clarendon Press.

Shuster CN, Barlow RB and Brockmann HJ (Eds.) (2003) ^ The American Horseshoe Crab Pages 163-164, Harvard University Press. ISBN 9780674011595.

^ Vosatka, ed. (1970). "Observations on the Swimming, Righting, and Burrowing Movements of Young Horseshoe Crabs, Limulus Polyphemus". The Ohio Journal of Science. 70 (5): 276-283. hdl:1811/5558.

^ Battelle BA (December 2006). "The eyes of Limulus polyphemus (Xiphosura, Chelicerata) and their afferent and efferent projections". Arthropod Structure & Development. 35 (4): 261-274. doi:10.1016/j.asd.2006.07.002. PMID 18089075.

Barlow RB (2009) ^ "Vision in horseshoe crabs" Archived 2024-03-04 at the Wayback Machine Pages 223-235 in JT Tanacredi, ML Botton and D Smith, Biology and Conservation of Horseshoe Crabs, Springer. ISBN 9780387899589.

Zaldívar-Rae J, Sapién-Silva RE, Rosales-Raya M, Brockmann HJ (2009). "American horseshoe crabs, Limulus polyphemus, in México: open possibilities". In J.T. Tanacredi, M.L. Botton, D.R. Smith (eds.). Biology and Conservation of Horseshoe Crabs. Springer. pp. 97-113. ISBN 9780387899589.

^ Jawahir AR, Samsur M, Shabdin ML, Rahim KA (2017). "Morphometric allometry of horseshoe crab, Tachypleus gigas at west part of Sarawak waters, Borneo, East Malaysia". AACL Bioflux. 10 (1): 18-24.

^ Cartwright-Taylor L, Lee J, Hsu CC (2009). "Population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda in Singapore" (PDF). Aquatic Biology. 8 (1): 61-69. doi:10.3354/ab00206. Archived (PDF) from the original on 2020-08-01.

^ Whitaker, David. "Horseshoe Crabs". South Carolina Department of Natural Resources. South Carolina Department of Natural Resources.

Mohamad Faizul Mat Isa (16 January 2021). "Belangkas : Potensi dan Masa Depan" [Horseshoe crabs: their potential and future]. Utusan Borneo (in Malay). Archived from the original on 17 January 2023 - via Universiti Putra Malaysia.

^ "Facts About Horseshoe Crabs and FAQ". Florida Fish and Wildlife Conservation Commission. Archived from the original on 4 June 2023.

^ "The Horseshoe Crab, limulus polyphemus: 200 Millions Years of Existence, 100 Years of study". 2002. Archived (PDF) from the original on 11 November 2020.

^ Carmichael RH, Brush E (2012). "Three decades of horseshoe crab rearing: A review of conditions for captive growth and survival". Reviews in Aquaculture. 4 (1): 32-43. doi:10.1111/j.1753-5131.2012.01059.x.

^ Hurton L (2003). Reducing post-bleeding mortality of horseshoe crabs (Limulus polyphemus) used in the biomedical industry (PDF) (M.Sc. thesis). Virginia Polytechnic Institute and State University. hdl:10919/36231. Archived from the original on 2013-06-22.

^ "Crash: A Tale of Two Species - The Benefits of Blue Blood - Nature - PBS". . 10 June 2008. Archived from the original on 10 October 2008.

^ Carmichael RH, Botton ML, Shin PK, Cheung SG, eds. (2015). Changing Global Perspectives on Horseshoe Crab Biology, Conservation and Management. Springer International Publishing.

^ Iwanaga S, Morita T, Miyata T, Nakamura T, Aketagawa J (1986-08-01). "The hemolymph coagulation system in invertebrate animals". Journal of Protein Chemistry. 5 (4): 255-268. doi:10.1007/bf01025424. ISSN 0277-8033. S2CID 84664449.

^ Iovenko C (17 December 2021). "Horseshoe crabs are in danger because everyone wants their blood". theverge.com. Archived from the original on 18 December 2021.

^ "Red knots get to feast on horseshoe crab eggs". Environment News Service. March 26, 2008. Archived from the original on 2015-09-24.

^ "Critter Class Hodge Podge (Horseshoe crabs and Wooly Bears)" (PDF). The Wildlife Center. October 26, 2011. Archived (PDF) from the original on 2015-04-02.

^ Ballesteros, Jesús A; Sharma, Prashant P (2019-03-27). "A Critical Appraisal of the Placement of Xiphosura (Chelicerata) with Account of Known Sources of Phylogenetic Error". Systematic Biology. 68 (6): 896-917. doi:10.1093/sysbio/syz011. ISSN 1063-5157. PMID 30917194.

^ Lamsdell, James C. (March 2016). Zhang, Xi-Guang (ed.). "Horseshoe crab phylogeny and independent colonizations of fresh water: ecological invasion as a driver for morphological innovation". Palaeontology. 59 (2): 181-194. doi:10.1111/pala.12220. ISSN 0031-0239.

^ Schwager, Evelyn E.; Sharma, Prashant P.; Clarke, Thomas; Leite, Daniel J.; Wierschin, Torsten; Pechmann, Matthias; Akiyama-Oda, Yasuko; Esposito, Lauren; Bechsgaard, Jesper; Bilde, Trine; Buffry, Alexandra D.; Chao, Hsu; Dinh, Huyen; Doddapaneni, HarshaVardhan; Dugan, Shannon (2017-07-31). "The house spider genome reveals an ancient whole-genome duplication during arachnid evolution". BMC Biology. 15 (1): 62. doi:10.1186/s12915-017-0399-x. ISSN 1741-7007. PMC . PMID 28756775.

^ Smith, Matthew Denman; Brockmann, H. Jane (2014-10-01). "The evolution and maintenance of sexual size dimorphism in horseshoe crabs: an evaluation of six functional hypotheses". Animal Behaviour. 96: 127-139. doi:10.1016/j.anbehav.2014.08.005. ISSN 0003-3472.

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Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to arachnids such as spiders, ticks, and scorpions.

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The oceans cover so much more of our planet than land, and yet we know so little about them. To me, this photo represents that idea as if someone is not looking for a ray, they possibly won't see one. When many people look at the ocean, they see just a vast expanse of blue and are oblivious to what lies underneath. So many are unaware of the great processes that occur in the ocean and how crucial they are to our planet. Although I would say I am more aware of these than some I would love to know more as the more you know the more you realize you don't now.

Phoebe H

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The ocean is so many things: a place of recreation, enjoyment, inspiration, and wonder; a source of food for mankind, and a home and hunting ground for untold creatures; an enormous dump; an unquiet neighbor in hurricanes and northeasters. I would like to learn more about it , though I suspect we will never plumb all its secrets. I am particularly interested in how other creatures are affected by changes in the ocean.

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Mysterious, unknown, mesmerising... It's most likely where everything started and probably where everything will end.

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I volunteer with penguins. I feel that in order to understand them better and help them as best I can, I need to know more about where they spend the majority of their time - the ocean.

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The ocean has one of the most rich biodiversity of the planet. The life begun there and even so, a great part of its life is still a mystery to us.

Abraão Cruz

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I loved reading books like 20 000 Leagues Under the Sea & other books about mystery sea legends. These days I'm involved with Sea Shephards doing beach cleans & would like to be more informed to be more useful in conservational efforts
Tasha

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These are boundless mysterious worlds that by discovery and understanding I belieour own lives become enriched. Learning about the animals, corals, plankton , currents etc..will help us better appreciate the wealth of life that exists in our world. The myriad varieties of life and the intelligence of instinct. It is time to appreciate the intelligence of the animals that inhabit those ecosystems. However, at the same time we need to wake up to the urgency to protect them with all our power and laws. Our lives are intimately bound up with the water systems but we still have so little understanding of the complexity of life and it's workings.
Alev

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The oceans sustain life and are full of such beauty and complexity and still so much mystery. I can't wait to learn more.
Esther

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The ocean, for me, contains much more than just water and sea creatures. According to the theory of evolution it is the place where everything started. I feel like a lot of damage has been done to the oceans and the living things in them by humans, but I also feel hopeful when I see and hear how many people are trying to protect the oceans. The ocean surely is a dark and mysterious place, scary even, but also full of things yet to discover. I chose this picture because out of all the ocean creatures, the octopi fascinate me the most.

Jane Liise Nurk

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Living in Jersey, Channel Islands, I have grown up having the sea right on my doorstep. I have a great interest for the ocean and hope this course will help me understand it better.
Peter Langlois.

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There's so much yet to discover.
Laura chambers

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The ocean means life to these seal pups who have been hand reared after being rescued by BDMLR.  After successful rearing and rehabilitation, they are released back to the sea.

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Oceans on my mind are synonym to mystery. The creatures that live in the deepest waters amaze me and make me feel that oceans have secrets that will never be revealed to us.
Zoi K.M.

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About 71% of the Earth's surface is covered by water, and as it is much less accessible than land to humans, there is much to be discovered

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For me, the ocean is a complete unknown of amazing animals. My brother lives in St. Thomas and he always sends me pictures of the amazing animals he sees while diving. The complete mystery of what's lurking down in the deepest parts of the ocean fascinates me.

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For me the ocean is a big mystery. I have never seen or been to the ocean so I get pretty worried when I know that we have only have serached 80% of it.

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ocean no just beautiful and full of wonders that we don't yet know about  , but it also important for our life
so we must save our oceans from pollution
we must put an end of climate change we must protect out oceans  ,

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I love going to the beach and looking out at the ocean. It gives me so many mixed feelings - fear of the unknown, hope through its vast expanse, life because of all the creatures and mysteries which reside within it. I want to protect it, I want to be a part of it, I want to solve at least one of its mysteries. - Jessica V

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The ocean always makes me feel free and either peaceful when it is calm or excited when it is wild! Janet

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The ocean, for me, is a mystery and freedom.
The ocean is equivalent to everyting an to nothing.
Of the ocean we see only the surface but there is an infinity of things to be know and discovered.
For this reason I believe that as image of the course would be chosen an image that remembers the exploration.
for me this course is equivalent discovering the mysteries of the ocean.
thank you of the attention:))

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Protect Our Seas

The photo is debris washed up on Midway Atoll.

Ann.

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What does the Ocean mean to me?  The Ocean is a self contained world that needs no help from "man" to survive (except to clean up Mans mess).  It is an incredible world with the perfect balance of life that supports all within it and does a most excellent job of housekeeping ;)
The marine life is as varied as the grains of sand on a beach and each amazing in their own beautiful and fascinating way.
Meet Albert, a Common Atlantic Octopus.  My first encounter with an octopus, as a child, scared me so that I was afraid of that which I couldn't see in the deep water for Many years.  Albert showed me the funny, playful, intelligent, shy, and yes, ticked off characteristics of an Octopus.  I now spend my free hours studying marine life, ecosystems, and the fascinating movements and geography of the vast Ocean.
Will you get me to jump in deep water where I can't see what's in it?  Albert didn't help me THAT much LOL.

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So little is known about the alien world of our oceans. I hope to learn all I can and even contribute to further findings in the years ahead.

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There is a vast world in the territory above the ocean, but its even bigger in the ocean. Its like another world with unexplored depths, amazing animals such as "nomura's jellyfish" live there and have incredible survivance abilities. Another territory with its mysteryes undercover, we harm it even withouth being there. There's so much to learn still..

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The diversity in the ocean has always been interesting to me, and not just the creatures that call the ocean home. The environment and the animals can be drastically different than others. This picture showcases that.-Miriam A

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Werri Beach
The sea always gives me A sense of freedom and excitement. Such a pity I get sea sick, so I just look, paddle on the edges and dream about the sea's mystery.

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Driving a boat out to a site, then running an exploration dive. No noise, no hassle, just water, bubbles, teamwork and deep satisfaction. Darryl Owen

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Boats and boating--Equipment and supplies

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When I was young, I feared the ocean and all that was in it. Deep water left me fearful and the thoughts of the creatures that dwelled within sent shivers down my spine...
That was until I took my first Scuba breath underwater when I was 14 - The world was new, unexplored, endless in my eyes - begging to be explored. Now, my life pursues our oceans; I am now a Marine Biologist with an FdSc in Marine Conservation & an BSc in Marine Biology. I've travelled many seas, yet the deep sea is where my next adventure lies. I pray that I may one day be there.

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Vast Expanse Full of Mana- Sam Flounders

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Vast Expanse Full of Mana- Sam Flounders

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"I am a citizen of the most beautiful nation on earth, a nation whose laws are harsh yet simple, a nation that never cheats, which is immense and without borders, where life is lived in the present. In this limitless nation, this nation of wind, light, and peace, there is no other ruler besides the sea." -Bernard Moitessier
I chose this quote quote as I think it adequately verbalizes feelings of the ocean in general and off shore in specific. I chose this picture to coincide with this quote as it is where I found these words to ring true- 1,000 miles off shore of Hawaii. I am overjoyed to see the test and inspiration of the ocean has found us all.

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My thoughts of the ocean is wide open spaces of water,  clear blue skies and a beautiful yacht.  I would dream of going off-shore but got my fun in dinghies.  I am fascinated by the ocean passing below me as I  fly to far-off destinations.   My image shows me at the Southampton Boat Show taking advantage of the free trials. Allen C.
(I got the post sorted
in the end!)

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Boats and boating--Equipment and supplies

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I am absolutely fascinated by the huge variety and diversity of life in the oceans.

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I studied marine biology at University and have continued to be interested, both scientifically and as an inspiration for art - hence the picture:

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Oceans are a big part of my life. I decided very young to study them (what I did, but changed my orientation for the PhD). Now I use my holidays to live my dream, running after sharks (se the tiger below), or remembering my studies (R. pachyptila , see below). For me, we need to protect them, as they are crucial for our terrestrial life, and because they are source of beauty, zen and equilibrium.

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The ocean means a lot to me, especially when I am diving. I feel at home underwater, the serenity and beauty that is beneath the surface is just breath taking. I took this photo of the Manta Ray while diving in the Maldives, I sat on the sea bed watching the gracious giants glide over my head. Showing off with twists and turns, I could of sat and watched all day. They are incredible creatures, and the ocean just astounds me with its biodiversity and its vast array of marine life.

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In order to protect our oceans we need people to learn more about them and how they influence our lives. Scuba diving gives me the opportunity to teach people more about sea life and that we should look after it, not destroy, pollute or simply not care as it doesn't affect me way of thinking.

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Though i'm an electric and electronic engineering student, it has always been my passion to learn and get myself familiarised to other fields as well. Infact the marine forms one of the gigantic habitats in the biosphere. In which the aquatic plants play a major role as far as the sustenence and balance of this giant habitat is concerned.
The health of aquatic vegetation is an important environmental indicator of overall ocean and estuary health.
Aquatic plants are vital to the welbeing of small invertebrates and fish. These small creatures are a food source for commercial and recreational fish.

Underwater vegetation in shallow coastal waters also supports a wide diversity of marine creatures by providing spawning, nursery, refuge, and foraging grounds for many species.

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Oceans give the live to the planet and help us with everything from food to capture the CO2, to distribute the heat to North and South places.

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Oceans give the live to the planet and help us with everything from food to capture the CO2, to distribute the heat to North and South places.

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The ocean has it's own ecosystem, water is such a different medium than what we are used to. We still have a long way to go in understanding the ecosystem that we don't live in.
It's wonderful and awe inspiring.

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I run rockpool rambles for people and spend scrambling about looking for rockpool creatures and everything else washed up by the seas. I am particularly fascinated by barnacles and keel worms.

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I have lived near the ocean nearly all of my adult life; first in Maine then in Greece. This photo is of a beach near my home on the island of Crete. I've been told by the locals that 30 years ago this area was covered in conch shells. Now? Nothing. Tourists have carted most of it away to display on their bookshelves. I am constantly amazed at the flora and fauna of our oceans, the effect of ocean currents on our weather, and the importance of this vast ecosystem to the health of our planet. With greater understanding can come a greater attention to reversing some of the damage caused by  humans.  (Having trouble uploading an image...stay tuned!)

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The world's oceans are the vessels of human sustainment. They absorb CO2, regulate the atmospheric temperature, provide nutrients to mankind and cover 70% of our planet.