# data[].attributes.headline
why is this cooler than the rest? (lihao)

# data[].attributes.subject
why is this cooler than the rest? (lihao)

# data[].attributes.body
Cnidarians can sting you and hurt you. You can't play with it but with the comb jelly, you can pick it up and play with it so comb jelly> Cnidarians
Comb Jelly > sponges because they can swim sponges only can filter feed. Quite boring. Hence forth.

# data[].attributes.headline
Comb jellies reproductive life cycle - Lance

# data[].attributes.subject
Comb jellies reproductive life cycle - Lance

# data[].attributes.body
Depending on the species on the comb jellies, some comb jellies are polymorphic, which alternates between the polyp and medusa during its life cycle. One of the polyps is used for asexual reproduction by budding. When these buds become mature and breakoff and releases the free-moving medusas.
The reproduction life cycle can also go through sexually partly due to the medusas either being a male or female. After fertilization, the blastula develops into the planula larvae.  Once the larvae attach to the substrate, it forms a new polyp. An example of a sea jelly is the mauve stinger, which reproduce both sexually and asexually

Reference: L04 lecture slides and BBC Wildlife Issue 7 Volume 40, June 2022

# data[].attributes.headline
Main Types of Comb Jellies: Cydippids, Lobates, and Beroids 

# data[].attributes.subject
Main Types of Comb Jellies: Cydippids, Lobates, and Beroids 

# data[].attributes.body
Cydippids:
All have rounded bodies—some spherical, some oval—with branched tentacles. (This means that their tentacles are fringed with smaller tentacles.) These tentacles can be withdrawn into the jelly's body into special sheaths or pouches on either side of their mouths.

Lobates:
Defined by two flattened lobes that extend from the typical rounded ctenophore body down below their mouths. They also have short tentacles and tend to grow larger than cydippids.

Beroids:
(Also known as "nuda") are sack-shaped and have no tentacles at all—but they do have a very large mouth, which they can zip shut very tightly.

Open ocean ctenophores are much less known. They come in a great diversity of forms. Some are shaped like belts (Cestida), while others don't float in the water column at all, but live on the seafloor! (These are known as benthic ctenophores.)

Reference:
Available at: https://ocean.si.edu/ocean-life/invertebrates/jellyfish-and-comb-jellies (Accessed: 10 November 2022)

# data[].attributes.attachment_link.readable_text
1. Home

2. Ocean Life

3. Invertebrates

4. http://ocean.si.edu/ocean-life/invertebrates/jellyfish-and-comb-jellies Jellyfish and Comb Jellies

Jellyfish and comb jellies are gelatinous animals that drift through the ocean's water column around the world. They are both beautiful-the jellyfish with their pulsating bells and long, trailing tentacles, and the comb jellies with their paddling combs generating rainbow-like colors. Yet though they look similar in some ways, jellyfish and comb jellies are not very close relatives (being in different phyla-Cnidaria and Ctenophora, respectively) and have very different life histories.

Both groups are ancient animals, having roamed the seas for at least 500 million years. And, in the modern age, they are having similar effects on ecosystems. As seawater temperature rises, predators of jellies are removed by fishing, more structures are built in seawater, and more nutrients flow into the ocean, some types of jellyfish and comb jellies may be finding it easier to grow and survive. Whatever the reason, huge explosions in jelly numbers (a jelly bloom) can disrupt fisheries, make for unpleasant swimming, or foul up the works of power plants that use seawater for cooling. Invasive jellies have also wreaked havoc in some parts of the world.

A Simple Body Plan

While jellyfish and comb jellies have several anatomical differences, the basics are the same. Both have two major cell layers: the external epidermis and the internal gastrodermis. (Ctenophores also have musculature in their in-between layer, the mesoderm, but it likely evolved separately from the mesoderm found in bilaterians like people.)

The gastrodermis lines the all-purpose gut and an opening where food enters and reproductive cells are released and taken in. Jellies have no need for a stomach, intestine, or lungs: nutrients and oxygen slip in and out of their cell walls through the gastrodermis or even their bodies' outer cells. The outer cells that make up the epidermis contain a loose network of nerves called the "nerve net." This is the most basic nervous system known in a multicellular animal. (See Brains of Jelly? for more.)

Between these layers is a gelatinous material called mesoglea, which makes up most of their bodies. (Although some small species have very thin mesoglea.) Jellyfish and comb jellies are 95 percent water and so, rightly, mesoglea is mostly water! It also contains some structural proteins, muscle cells, and nerve cells, forming a kind of internal skeleton.

Comb Jellies' Unique Features

Comb jellies are named for their unique feature: plates of giant fused cilia, known as combs, which run in eight rows up and down their bodies. The combs act like tiny oars, propelling the comb jelly through the water. Many microscopic organisms, such as bacteria, also use cilia to swim-but comb jellies are the largest known animals to do so. The comb-rows often produce a rainbow effect. This is not bioluminescence, but occurs when light is scattered in different directions by the moving cilia.

Until 2015 scientists believed that comb jellies removed their waste via their "mouth," or what was believed to be the one hole in their body plan. A new study showed that comb jellies in fact release indigestible particles through pores on the rear end of the animal. This discovery adds another piece to the evolutionary puzzle of when animals evolved to have anuses.

Many comb jellies have a single pair of tentacles (often each tentacle is branched, giving the illusion of many tentacles) that they use like fishing lines to catch prey. They are armed with sticky cells (colloblasts) and unlike jellyfish, the tentacles of comb jellies don't sting. (See The Stings: Nematocysts and Colloblasts for more.)

Jellyfishes' Unique Features

(K. Raskoff, Monterey Peninsula College, Hidden Ocean 2005, NOAA.)

Jellyfish transition between two different body forms throughout their lives. The familiar body plan that looks like an upside down bell with tentacles hanging down from the inside is called the medusa. The polyp, the other cnidarian body plan, is the opposite, with the mouth and tentacles above, like a sea anemone. (See more in Reproduction & Lifecycle.)

Jellyfish also have a stinging adaptation that is unique to them and their close relatives (including sea anemones and hydras): nematocysts, or stinging cells. (See The Stings: Nematocysts and Colloblasts for more.)

Size

Jellyfish and comb jellies vary greatly in size depending on the species. Most jellies range from less than half an inch (1 cm) wide to about 16 inches (40 cm), though the smallest are just one millimeter wide! The largest jellies are the Lion's Mane Jellyfish (Cyanea capillata), which can be almost 6 feet wide (1.8 m) with tentacles over 49 feet (15 m) long. Larger individuals have been seen, but they are not typical. Venus's girdle (Cestum veneris), a belt shaped comb jelly, can be 40 inches (1 meter) long.

The Nervous System

Brains of Jelly?

Jellies don't have brains as we typically think of them: rather, they have a network of neurons ("nerve net") that allows jellies to sense their environments, such as changes in water chemistry indicating food or the touch of another animal. The nerve net has some specialized structures such as statocysts, which are balance sensors that help jellies know whether they are facing up or down, and light-sensing organs called ocelli, which can sense the presence and absence of light.

Additionally, some jellyfish have sensory structures called rhopalia, which contain receptors to detect light, chemicals and movement. One group of jellyfish, the cubozoan jellyfish, have complex eyes with lenses, corneas and retinas in their rhopalia. Although they respond to visual stimuli, scientists don't know how the jellyfish interpret the images created by their eyes since they don't have a brain with which to process them. Their nerve ring, a ring-shaped concentration of nerves found in jellyfish, seems to be involved, however.

A 2017 study of the upside-down jellyfish, Cassiopea, found that a brain is not required to experience sleep. At night Cassiopea enters a sleep-like state where it pulses less frequently than during the day and is slow to respond to disturbances. When kept awake throughout the night, the next day the jellyfish appear to be tired-their pulsing was noticeably slower than if they had a solid night of sleep. It is the first time an animal without a brain was observed sleeping. The discovery suggests sleep among all animals is an ancient characteristic with a shared evolutionary beginning, considering the neural network of jellyfish evolved before centralized nervous systems like a brain.

Diversity

Types of Jellyfish

Jellies are found in oceans worldwide, in shallow and deep water, and a few can even be found living in freshwater. They have been found floating in the deepest parts of the ocean, like at the bottom of the Mariana trench.

All jellyfish are Cnidaria, an animal phylum that contains jellies, sea anemones, and corals, among others. There are more than 10,000 species of Cnidaria, and less than 4,000 of these are Medusazoa-those animals we think of as jellyfish. Those 4,000 jellyfish can be divided into four different groups.

SCYPHOZOA are the most familiar jellyfish, including most of the bigger and more colorful jellies that interact with humans, and are sometimes called "true jellyfish" for this reason. Scyphozoa spend most of their lives in the medusa body form, and there are at least 200 species.

HYDROZOA are jellyfish look-alikes but not in the same group as the "true jellyfish." The swimming medusa stages of this group are often small and inconspicuous, whereas the bottom-dwelling polyps, or hydroids, usually take the form of large colonies. (See Reproduction & Lifecycle.) In the water column, the colonial siphonophores may be quite spectacular. These include the notorious Portuguese Man-o-Wars and many deep-sea forms, some of which stretch out up to 50 meters in length like giant fishing nets. Colonial siphonophores are composed of many specialized individuals called zooids that are genetically identical because they all come from a single fertilized egg. In 2016, researchers discovered what they believe to be a new hydrozoan species of Crossota, 12,140 feet (3,700 meters) deep within the Mariana Trench. Floating in the water column like a glowing spaceship, this Crossota jellyfish is an exception to most hydrozoans and will spend the majority of its life as a large medusa. There are around 3,700 species of Hydrozoa.

CUBOZOA are the box jellyfish, named for their box-like bells. Some cubozoans, such as the sea wasp (Chironex fleckeri), produce some of the most potent venom known. Cubozoan jellyfish also have a more developed nervous system than other jellyfish, including complex eyes with lenses, corneas and retinas. Some even engage in elaborate (for a jellyfish) courtship behavior! There are at least 36 species. In 2011, Allen Collins, a jellyfish expert at the Smithsonian, discovered a new species, which was named Tamoya ohboya in a public naming contest. (Listen to a podcast about box jellies.)

STAUROZOA are the stalked jellyfishes, which don't float through the water like other jellies, but rather live attached to rocks or seaweed. They are trumpet-shaped, and mostly live in cold water. There are around 50 staurozoan species, many notable for their unique combination of beauty and camouflage.

Types of Comb Jellies

Compared to jellyfish, there are far fewer species of ctenophores: only 100-150 species have been found, but quite a few are out there yet to be discovered and fully documented. The best-known comb jellies are those found close to shore because, there, they are most likely to run into people. Those can be roughly divided into three groups.

CYDIPPIDS all have rounded bodies-some spherical, some oval-with branched tentacles. (This means that their tentacles are fringed with smaller tentacles.) These tentacles can be withdrawn into the jelly's body into special sheaths or pouches on either side of their mouths.

LOBATES are defined by two flattened lobes that extend from the typical rounded ctenophore body down below their mouths. They also have short tentacles and tend to grow larger than cydippids.

BEROIDS (also known as "nuda") are sack-shaped and have no tentacles at all-but they do have a very large mouth, which they can zip shut very tightly.

Open ocean ctenophores are much less known. They tend to be very fragile because they don't have to endure rough coastal waves; many of them are so fragile that they cannot be collected by submersibles and are known only by photographs. They come in a great diversity of forms. Some are shaped like belts (Cestida), while others don't float in the water column at all, but live on the seafloor! (These are known as benthic ctenophores.)

Comb jellies live throughout the world's ocean, although most species prefer warmer water.

Evolution

How Closely Related?

Jellyfish and comb jellies are in different phyla, but scientists have long argued over whether they have an especially close relationship apart from the rest of the animal kingdom. To distinguish them, all Cnidaria and Ctenophora were once described as Coelenterata-but that term is no longer commonly used.

To this day, some researchers believe they are sister groups, while others think they are not closely related. Some argue that a new fossil from the Chengjiang fossil site in China and a peculiar fossil in the Burgess Shale are similar enough to jellyfish that they might be ancient comb jellies that had recently split from the jellyfish lineage. Either way, there are still plenty of other questions to argue about, such as how long ago the two groups diverged, and even whether ctenophores might be the most ancient group of animals, diverging even earlier than sponges in the animal tree of life. These arguments continue because, as some of the simplest animals alive today, understanding their place in the tree of life helps people understand how all other animals-including people-evolved.

Fossil Jellies

Whichever came first, comb jellies and jellyfish (and other Cnidarians) made an important step in evolutionary history: they are the earliest known animals to have organized tissues-their epidermis and gastrodermis-and a nervous system. They're also the first animals known to swim using muscles instead of drifting with the whims of the waves.

The oldest ancestors of modern day jellies lived at least 500 million years ago, and maybe as long as 700 million years ago. That makes jellyfish three-times as old as the first dinosaurs!

Because jellies have no bones or other hard parts, finding jellyfish fossils is rare. But in 2007, a group of scientists including Allen Collins from the Smithsonian National Museum of Natural History, discovered some beautifully-preserved jellyfish fossils buried in Utah from 505 million years ago. From around the same period, scientists have also found well-preserved comb jelly fossils in the Burgess Shale.

Fossils described in 2019 from the Quingjiang site in southern China are some of the best preserved Cambrian fossils ever found, with the cilia and plates easily visible. Scientists are optimistic this discovery will help tease out the relationship between jellyfish and comb jellies.

Predators and Prey

Jellyfish and ctenophores are carnivorous, and will eat just about anything they run into! Most jellies primarily eat plankton, tiny organisms that drift along in the water, although larger ones may also eat crustaceans, fish and even other jellyfish and comb jellies. Some jellyfish sit upside down on the bottom and have symbiotic algae (zooxanthellae) in their tissues, which photosynthesize, and so get much of their energy the way plants do.

While their nematocysts and colloblasts do help them defend themselves, plenty of animals manage to catch and eat jellies: more than 150 animal species are known to eat jellies, including fish, sea turtles, crustaceans, and even other jellyfish. Jellies are the favorite food of the ocean sunfish ( Mola mola) and endangered leatherback turtle ( Dermochelys coriacea), which will migrate thousands of miles for the gelatinous delicacy. Young jellyfish are small enough to be part of the general zooplankton population and are eaten by many animals.

Humans also eat jellyfish: people have fished for jellies for at least 1700 years off the coast of China. Some 425,000 tons (more than 900 million pounds) of jellyfish are caught each year by fisheries in 15 countries, and most are consumed in Southeast Asia. Eating jellyfish may become more common around the world as we overfish more preferable fish species.

Feeding Adaptations

The Stings: Nematocysts and Colloblasts

Jellyfish and ctenophores both have tentacles with specialized cells to capture prey: nematocysts and colloblasts, respectively. Jellyfishes' nematocysts are organelles within special cells (cnidocytes) that contain venom-bearing harpoons. The cell is activated upon touch or chemical cue, causing the harpoon to shoot out of the cell and spear the prey or enemy, releasing toxin-a process that takes only 700 nanoseconds. A small number of jellyfish are very toxic to humans, such as the box jellyfish ( Chironex fleckeri) and Irukandji jellyfish ( Carukia barnesi), which can cause severe reactions and even death in some people.

Many comb jellies have colloblasts lining their tentacles, which work like nematocysts but release glue instead of venom. Upon touch, a spiral filament automatically bursts out of colloblast cells that releases the sticky glue. Once an item is stuck, the comb jelly reels in its tentacle and brings the food into its mouth. One species of ctenophore ( Haeckelia rubra) recycles nematocysts from hydrozoan jellyfish it consumes and uses these to stun and kill prey.

Many Ctenophores, Many Ways to Feed

Comb jellies come in many shapes and sizes, and so within the group there are many ways to feed. The rounded and tentacled cydippids have branched tentacles lined with colloblasts that they use, in the traditional jelly style, like a fishing line to trap food and bring it to their mouths.

The lobate ctenophores have two flattened lobes that reach below their mouths. Special cilia waving between the lobes generate a current to pull planktonic food between the lobes and into the jelly's mouth, allowing them to feed on plankton continuously. They also use colloblast-lined tentacles to catch food.

The tentacle-less beroids depend on their large mouths. Instead of catching food with colloblasts, they swallow their prey (often other ctenophores!) whole and then clamp their mouths shut, giving them no escape route. Inside their mouths they have small cilia that act as teeth, pulling food apart, which also direct the food into the comb jelly's gut.

Defense Adaptations

Color and Bioluminescence

Many jellyfish and comb jellies are able to produce light-an ability known as bioluminescence. They have proteins in some tissues that undergo a chemical reaction to produce blue or green light in response to stimuli such as touch. No one's quite sure why jellies bioluminesce, but it seems to be mainly a defense tactic. A bright enough flash could be enough to startle a predator-or to attract an even bigger predator to make the jelly's predator into prey.

Jellies have also adapted their body color to camouflage in the darkness. Most are nearly colorless and transparent, so they can be difficult for predators to see. However, some deep sea jellyfish and comb jellies are a bright red or orange color. Why would they be red instead of black to blend in with the dark water? Red cannot be seen in dark water (deeper than 200 meters), so there's no greater protection from black than red. But red is preferred to black because pigment is easier for animals to produce. Some deep sea jellies just have dark red guts, possibly serving to mask luminescent prey from other larger predators with eyes.

Jellyfish: Medusa and Polyp Switch-Off

Jellyfish have a complex life cycle: a single jellyfish reproduces both sexually and asexually during its lifetime, and takes on two different body forms.

An adult jellyfish is called a medusa, which is the familiar umbrella-shaped form that we see in the water. Medusa jellyfish reproduce sexually by spawning-the mass release of eggs and sperm into the open ocean-with entire populations sometimes spawning all together. Male and female jellyfish (there aren't many hermaphrodites) release the sperm and eggs from their mouths. In most species, fertilization takes place in the water; in others, the sperm swim up into the female's mouth and fertilize the eggs within.

The fertilized eggs then develop into planulae (singular: planula), which are ciliated free-swimming larvae shaped a bit like a miniature flattened pear. After several days of development, the planulae attach to a firm surface and transform into flower-like polyps. The polyps have a mouth and tentacles that are used to feed on zooplankton.

Polyps reproduce asexually by budding-when a polyp divides roughly in half to produce a new genetically identical polyp-or they can produce or transform into medusae, depending on the type of jellyfish. Hydrozoan polyps bud medusae from their sides; cubozoan polyps each transform into a medusa.

In schyphozoans, a process called strobilation takes place (shown in video and in diagram). During strobilation, a polyp splits into 10-15 plate-like segments stacked atop one another in a tower called a strobila. After a segment separates from the strobila, it is called an ephyra, a juvenile jellyfish. Ephyrae mature into the medusa form.

Most jellyfish are short lived. Medusa or adult jellyfish typically live for a few months, depending on the species, although some species can live for 2-3 years in captivity. Polyps can live and reproduce asexually for several years, or even decades.

One jellyfish species is almost immortal. Turritopsis nutricula, a small hydrozoan, can revert back to the polyp stage after reaching adult medusa stage through a process called transdifferentiation. This is the only animal known to do so.

Comb Jellies

In comparison to the jellyfish, comb jellies have a very simple lifecycle. Most species are hermaphroditic and able to release both eggs and sperm into the water, which drift with the waves until they find other gametes. Because most species have both male and female gametes, it's thought that they can self-fertilize as well.

This method may not seem very efficient, since it's likely that most of the gametes never find a match. But ctenophores make up for this by releasing them every day. If they run out of food while producing so many eggs and sperm, they can shrink and hunker down until they run into more food and can start reproducing again.

Once eggs and sperm find each other, the embryo develops into a larva that looks just like a small adult ctenophore-and, from there, all it has to do is grow up.

One species ( Mertensia ovum) can reproduce even when it is still larva, and scientists think other species are also able to reproduce at a young age. This means that comb jelly populations can grow very fast under certain conditions.

Jellyfish Blooms

Around the world, vast aggregations of jellyfish and comb jellies seem to be more common. These aggregations are known as "jellyfish blooms" or "jellyfish outbreaks," which can cause a wide array of problems. Too many jellies in the water can be a danger to swimmers, forcing towns to close their beaches. Jellies have clogged up machinery at coastal power plants, causing power outages. They can interfere with fisheries by eating fish larvae, and fisherman catch jellies instead of the fish they want. Where they occur, blooms of jellyfish even change seawater chemistry. Scientists hope to address this problem through the discovery of a practical application for jellyfish, like substituting jellyfish for the fish used in aquaculture feed. Jellyfish mucus, which has been shown to bind to microplastics, may even one day be used in water treatment facilities to help combat the world's growing plastic problem.

Why are jellies becoming more common around the world? It seems likely that their spread is human-caused, although some scientists have argued that the blooms are part of a natural cycle. If the blooms are human-caused, there are several probable culprits.

OVERFISHING Over the past two decades, between 100 and 120 million tons of marine life have been removed from the ocean by fisheries each year on average. A lot of these marine species, including fish and invertebrates such as squid, eat some of the same food that jellies do: mainly, zooplankton. As these other predators of plankton are fished from the sea, jellies have less competition for food, and are able to grow and reproduce with fewer limits.

NUTRIENTS When fertilizers runoff from the rivers to the seas, they can create dead zones: areas of ocean where little life survives. The nitrogen and phosphorus in fertilizer helps phytoplankton grow very quickly, and there can be so many of these single-celled plant-like animals that they deplete oxygen from the water. Most animals can't survive in these conditions, but many jellies can better tolerate low-oxygen environments.

CLIMATE CHANGE The ocean is warming, and this might give some jellies a boost. The warmer water could help jelly embryos and larvae develop more quickly, allowing their populations to grow more quickly. And jellies that prefer warmer water will have more area to live in. However, this could also hurt some species as cold-water jelly species see their habitat shrink.

SUBMARINE SPRAWL Many industries, such as shipping, drilling and aquaculture, build docks, oil platforms and other structures in the water-sometimes referred to as "ocean sprawl"-which can serve as nurseries for jellyfish. To undergo their polyp stage, jellyfish need solid surfaces to settle upon. It's much easier for jellyfish polyps to attach to man-made structures made of wood, brick and concrete than sand. Ocean sprawl provides more and better habitat for jellyfish to reproduce and complete their lifecycles.

Invasive Species & Fisheries

(Marco Faasse, World Register of Marine Species)

Jellies are very good at surviving: they have broad diets, reproduce quickly, can shrink down if food runs out and then revive, and tolerate low-oxygen water. So, as you can imagine, they are also very good at thriving in new ecosystems once they arrive.

In the 1980s, the sea walnut (Mnemiopsis leidyi), a type of comb jelly, was brought to the Black Sea in ship ballast water. It reproduced and spread quickly, gobbling up zooplankton and leaving little behind for the larvae of commercial fish species, including anchovy, scad and sprat. Within a decade, the comb jellies took over the Black Sea and many of the fish populations collapsed, bringing local fisheries down with them. In a stroke of accidental luck, a different species of comb jelly ( Beroe ovum)-a predator of the sea walnut-was brought over in a ship, and it's helping to bring down the population. A similar story of fishery collapse coinciding with jellyfish blooms is playing out off the coast of Japan.

However, the collapse of a fishery doesn't always end in jellyfish. A crash in the pollock and walleye fishery in the Bering Sea left an opening for jellyfish but, after reigning for a few years, the jellies gave up their crown as the fish returned. And when the Peruvian anchovy fishery collapsed in the 1970s, no jellyfish swarmed in to take their place.

# data[].attributes.attachment_link.description
Home Ocean Life Invertebrates http://ocean.si.edu/ocean-life/invertebrates/jellyfish-and-comb-jellies Jellyfish and Comb Jellies Jellyfish and comb jellies are gelatinous animals that drift through the ocean's water column around the world. They are both beautiful-the jellyfish with their pulsating bells and long, trailing tentacles, and the comb jellies with their paddling combs generating rainbow-like colors.

# data[].attributes.body
- mainly zooplankton (plankton live mostly on the surface, so sea jellies float near the surface to obtain zooplankton)
- other sea jellies
- crustaceans ( e.g. lobster, shrimp, crabs) : harder for sea jellies to catch and digests so are not a main source of energy for them.
- plants (e.g. seaweed, algae, phytoplankton) : only when they are young
- small fishes and their eggs
references:
- American Oceans (N.d) What do jellyfish eat? Available at: What Do Jellyfish Eat & How Do They Do It? - American Oceans (accessed: 10/11/2022)

# data[].attributes.attachment_link.readable_text
Jellyfish lurk in the waters of every ocean in the world, so one could expect them to have a varied diet.

From shallow bays to the deepest trenches of the ocean, these invertebrates feed on whatever is available in their habitats.

Today, we'll be diving in to answer: what do jellyfish eat? There are around 2000 known species of jellyfish on the planet.

Regardless of species, they tend to be carnivorous-meaning they feed on other animals. However, jellyfish will occasionally consume plant matter as well.

So, what do jellyfish eat? Here are the main components of the average jellyfish diet.

The Jellyfish Diet

Plankton

Plankton-zooplankton in particular- make up the majority of a jellyfish's diet. They live everywhere there is saltwater, so these microscopic organisms are an easy source of nutrients.

To feed on plankton, a jellyfish simply needs to float near the surface of the ocean; this is where most planktons live, as they require plenty of sunlight to survive.

As a jellyfish drifts through the water, it captures the surrounding planktons in their stingers with ease.

Crustaceans

Some larger jellyfish species may feed on crustaceans. This includes lobsters, crabs, and even shrimp.

Unlike plankton, however, crustaceans are a bit more difficult for jellyfish to catch. Because of this, they are not a regular food source for jellyfish.

When a jellyfish does manage to catch a crustacean, it will trap it within its stingers. These stingers will then paralyze their prey.

The jellyfish will then swallow the crustacean whole, absorbing nutrients such as protein and omega acids as it digests.

Plants

While these creatures are mainly carnivorous, some jellyfish will eat plants while they are young. Seaweed, algae, and phytoplankton are among some of the plant life that jellyfish will consume.

Plants are a convenient source of nutrients for young jellyfish. They are abundant in nearly all parts of the ocean, and as they drift through the water, they are easy to catch and eat.

Plants such as seaweed are very nutrient-dense, especially in minerals such as iron or folate. So while jellyfish are mainly carnivores, consuming plant matter during their adolescence can still help their development.

Small Fish

Small fish and their eggs are another significant part of the jellyfish diet. They are protein-dense and full of other essential nutrients that help jellyfish grow and thrive.

Jellyfish will often linger in areas where smaller fish live. If a fish swims into their mass of stingers, the jellyfish will then paralyze them and swallow them whole.

Jellyfish may also lurk in fish's dens in search of their eggs. Like small fish, they are a quick and easy source of protein.

Other Jellyfish

There are some instances where a jellyfish will consume its own kind. In these cases, it is usually an adult jellyfish eating their offspring, or sometimes a smaller jellyfish of a different species.

This is not common behavior for these sea creatures, however. Jellyfish have little to no nutritional value.

So consuming others is often not worth the effort. In general, jellyfish only partake in cannibalism when other food sources are scarce.

How Do Jellyfish Collect Food?

Jellyfish are opportunistic hunters-meaning they do not actively chase down prey but instead prefer to catch whatever is within reach.

They collect prey such as plankton by simply floating in the water and catching what they can with their stingers.

To catch other prey such as fish, crustaceans, or eggs, they lurk in areas where those animals tend to gather.

From there, they wait for prey to come near. Once the food is within reach, jellyfish rely on their stingers to do the rest.

Jellyfish stingers will release venom that they use to trap and paralyze their prey. Once the jellyfish has paralyzed its prey, it is ready to feed.

How Do Jellyfish Eat?

After a jellyfish has captured prey, it uses its tentacles to bring the food toward a hole at the base of its body.

This hole has multiple functions; they use it to eat, swim and even expel waste after they eat. Jellyfish do not have teeth to chew.

Instead, they swallow their prey whole. Once the food is in their stomach, enzymes will break down the materials and absorb the nutrients.

Once they've extracted all of the nutrients from their food, the waste exits their body from the same hole.

Final Thoughts

Jellyfish play an essential role in the ocean's food chain. They consume a variety of smaller organisms, including microscopic plankton, various crustaceans, and even other jellyfish.

In turn, jellyfish are a significant part of other sea creatures' diets. Sunfish and turtles, for instance, often rely on jellyfish as a food source.

Some humans even catch jellyfish and serve them in a variety of dishes. Overall, jellyfish play an essential role in the ocean's ecosystem.

With their unusual feeding habits and varied diet, they are nothing short of unique creatures. Looking for more fun jellyfish facts? Check out what is considered the deadliest jellyfish right here.

# data[].attributes.attachment_link.title
What Do Jellyfish Eat & How Do They Do It? - American Oceans

# data[].attributes.attachment_link.description
Jellyfish lurk in the waters of every ocean in the world, so one could expect them to have a varied diet. From shallow bays to the deepest trenches of the ocean, these invertebrates feed on whatever is available in their habitats. Today, we'll be diving in to answer: what do jellyfish eat?

# data[].attributes.body
is constituted by a complex network of meridional channels that cross the periphery towards the inner portion of their central digestive channel. Digested foods can be excreted through the mouth or anal pores.

Reference:
Available at: https://ourmarinespecies.com/c-other-species/comb-jellies/ (Accessed: 10 November 2022)

# data[].attributes.attachment_link.title
Comb Jellies: Characteristics, habitats, reproduction and more...

# data[].attributes.attachment_link.description
Comb jellies are transparent, jelly-like invertebrates with stunning iridescent color bands. Join us to learn everything about them.

# data[].attributes.headline
Ctenophores are able to produce light (bioluminescent) lihao

# data[].attributes.subject
Ctenophores are able to produce light (bioluminescent) lihao

# data[].attributes.body
Comb jellies are able to produce lights due to them possessing genes that create calcium activated proteins called photoproteins in cells called photocytes. When activated, these proteins produce light, allowing for the cells in the comb jelly to light up.

These lights can allow for:

Scaring off of predators

Attracting prey

Communication with own species

Reference:Genome.gov. (n.d.). Bioluminescent comb jellies begin to shed light on the evolution of vision. [online] Available at: https://www.genome.gov/27551984/2012-news-feature-bioluminescent-comb-jellies-begin-to-shed-light-on-the-evolution-of-vision#:~:text=Comb%20jellies%27%20ability%20to%20generate [Accessed 10 Nov. 2022].

# data[].attributes.body
Comb jellies can eat others of their own kind, even ones that are larger than themselves. They do this by biting off chunks from prey using special cilia structures in their mouth.

Fun facts about comb jellies. (n.d.). Retrieved November 10, 2022, from https://www.florida-adventurer.com/blog/fun-facts-about-comb-jellies-

# data[].attributes.body
According to the Smithsonian National Museum of Natural history, the comb jellies are at least 500 million years old.

Fun facts about comb jellies. (n.d.). Retrieved November 10, 2022, from https://www.florida-adventurer.com/blog/fun-facts-about-comb-jellies-

# data[].attributes.body
- Marine creature (does not live in fresh water)
- found in every ocean in the world, although most species prefer warmer water.

Reference:
Available at: https://ocean.si.edu/ocean-life/invertebrates/jellyfish-and-comb-jellies (Accessed: 10 November 2022)

# data[].attributes.body
- Their bodies are mostly water (about 95%) with only 5% of solid matter.
- they lack organs like brain and hearts, and hence do not have blood. However, have an elementary nervous system that helps them detect light, smell and respond to other stimuli. They also have a digestive system containing a stomach, intestine, mouth and anus. (mouth and anus are the same opening)
- They are made of 3 layers, Epidermis (the outer layer), mesoglea (middle layer), which is made of a thick, elastic and jelly-like substance, and gastrodermis ( inner layer)
- body parts: oral arms, hood, stomach pouch, eye spots, gonads, mouth/anus and tentacles

references:
- NOAA(2021) What are jellyfish made of? Available at: What are jellyfish made of? (noaa.gov) (accessed: 10/11/2022)
- sea jelly body components - Bing images

# data[].attributes.attachment_link.readable_text
Fascinating, elegant, and mysterious to watch in the water, take a jellyfish out of the water, and it becomes a much less fascinating blob. This is because jellyfish are about 95 percent water.

Fascinating, elegant, and mysterious to watch in the water, take a jellyfish out of the water, and it becomes a much less fascinating blob. This is because jellyfish are about 95 percent water.

Lacking brains, blood, or even hearts, jellyfish are pretty simple critters. They are composed of three layers: an outer layer, called the epidermis; a middle layer made of a thick, elastic, jelly-like substance called mesoglea; and an inner layer, called the gastrodermis. An elementary nervous system, or nerve net, allows jellyfish to smell, detect light, and respond to other stimuli. The simple digestive cavity of a jellyfish acts as both its stomach and intestine, with one opening for both the mouth and the anus.

These simple invertebrates are members of the phylum Cnidaria, which includes creatures such as sea anemones, sea whips, and corals. Like all members of the phylum, the body parts of a jellyfish radiate from a central axis. This "radial symmetry" allows jellyfish to detect and respond to food or danger from any direction.

Jellyfish have the ability to sting with their tentacles. While the severity of stings varies, in humans, most jellyfish stings result only in minor discomfort.

# data[].attributes.attachment_link.keywords[]
national oceanic and atmospheric administration

# data[].attributes.attachment_link.description
Only about five percent of the body of a jellyfish is solid matter; the rest is water

# data[].attributes.headline
Comb jellies - Phylum Ctenophora (comb bearers)

# data[].attributes.subject
Comb jellies - Phylum Ctenophora (comb bearers)

# data[].attributes.body
• Basal eumetazoans (animals with tissues and organs)
• Comb jellies possess eight rows of fused cilia (‘hair’) known as combs for movement through water.
• Swallow the prey whole to be digested by enzymes.

• Comb jellies tentacles possess cells called
colloblasts that produce sticky strands to trap prey.
• Have a nerve net, but lacks a complicated nervous system.