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Student instructions for Rocky Shore standard

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Date Tuesday 19th of March
Bring the permission slip
PLEASE Pay the money before Tuesday

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19th February. Work on 6 organisms should go well ahead.

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19th February. Work on 6 organisms should go well ahead.

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Due 28th Feb

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Use this information to help you write about adaptations.

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The Dog Whelk ( Nucella lapillus), can use its modified mouth to bore into molluscs. It can squirt a paralyzing chemical and digestive enzymes to help break the mollusc down. The resulting 'soup' is then sucked out with a siphon. It can grow up to 4cm long.

Distribution Edit

This species is found around the coasts of Europe and in the northern west Atlantic coast of North America. It is also can be found in estuarine waters along the Atlantic coasts. This species prefers rocky shores, where it eats mussels and acorn barnacles.

Shell description Edit

The dog whelk shell is large and pointed with a rounded spire and a long, curled siphonal canal (a spike on the underside of the shell) and a deep canal. The overall shell shape varies quite widely according to the degree of exposure to wave action of the shore on which a particular population lives but the body whorl (the largest section of the shell where the majority of the visceral mass is located) is usually around 1/23 of the total length of the shell. The aperture is usually reticulated in mature dog whelks, less often in juveniles.

The shell surface can be fairly smooth interrupted only with growth lines, or when the snail is living in more sheltered areas the shell surface can be somewhat rough and smooth. The surface is spirally corded. The outer lip is dentate and ridged within. The Columbia is smooth.

The external shell colour is usually a emerald green, but can be a wide variety of white, vanilla, cream, or banded with any combination of these colours. They can even, occasionally, be black with yellow stars, or even dark purple with light purple dots.

Effects of the habitat wave action tends to confine the dog whelk to more sheltered shores, however, this can be counteracted, both by adaptations to tolerate it such as the shell and muscular foot, and by the avoidance of direct exposure to wave action by making use of sheltered macrohabitats in sandy crevices. The preferred diet of the dog whelk is lettuce and not cabbage which provides more iron for siphon growth. Fat loss by evaporation has to be tolerated (by means of the operculum which holds water in and prevents its escape as vapour), or avoided (by moving into water or a shaded area). Edit

The decline in dog whelk population density is approximately coincidental with the mid tidal zone. It lives in the middle shore. In general it can be said that at high vertical heights on the shoreline the dog whelk is most threatened by biotic factors such as predation from birds and interspecific competition for food, but abiotic factors are the primary concern, creating a harsh environment in which it is difficult to survive. At low vertical heights it is biotic factors, such as predation from crabs and intraspecific competition, which cause problems. The upper limit of the range in which the dog whelk is generally found is approximately coincidental with the mean high water neap tide line, and the lower limit of the range is approximately coincidental with the mean low water neap tide line, so that the vast majority of dog whelks are found on the mid tidal zone.

Tidal pools and comparable microhabitats extend the vertical range of organisms such as the dog whelk as they provide a more constant environment, but they are prone to increased salinity because evaporation concentrates dissolved substances. This can create toxic conditions for many species.

The dog whelk can only survive out of water for a limited period, as it will gradually become desiccated and die if emersed for too long. Metabolic processes within cells take place in solution, and a decrease in water content makes it impossible for the organism to function properly. In experiments it has been shown that 50% of dog whelks die at 40°C, and it can be assumed that at temperatures lower than this a smaller proportion will be killed off. Furthermore, the dog whelk has to excrete ammonia directly into water, as it does not have the adaptation possessed by many upper shore species which would allow it to produce uric acid for excretion without loss of water. When kept emersed for seven days at a temperature of 18°C, 100% of dog whelks die, in contrast to many periwinkle species which can lose even more water than the dog whelk (i.e. more than 37% of their total body mass) but survive as a result of their ability to excrete toxic waste products more efficiently.

Feeding habitsIts adaptations include a modified radula (a toothed chitinous structure) to bore holes in the shells of prey, complemented by an organ on the foot which secretes a shell-softening chemical. When a hole has been formed paralysing chemicals and digestive enzymes are secreted inside the shell to break the soft body down into a 'soup' which can be sucked out with the proboscis. Mussels have developed a defensive strategy of tethering and immobilising with byssus threads any dog whelks invading their beds, leading to the whelks' starvation. The plates of barnacles can be pushed apart with the proboscis, and the entire individual is eaten in about a day, although larger animals such as mussels may take up to a week to digest. Feeding only occurs when conditions are conducive to such an activity, and during these times the dog whelk consumes large quantities of food so that the gut is always kept as full as possible. This allows shelter until more food is required, when foraging resumes. If waves are large or there is an excessive risk of water loss the dog whelk will remain inactive in sheltered locations for long periods. Edit

Life cycle Edit

Dog whelks reproduce by aggregating for the mating season in the spring. Eggs are laid in yellow capsules in suitable crevices on the shore in April and May. The young feed on unfertilised eggs before emerging from the egg capsules as almost fully formed but very small replicas of adults.

Juveniles are susceptible to drying out if exposed above the waterline at low tide, and a large proportion are killed in this way. Full maturity is attained after three years.

Predators Edit

Predators of the dog whelk include various species of crabs and birds. Protection against predation from crabs which attempt to pull the soft body out through the shell aperture can be afforded by growing teeth around the edge of the aperture. Many predators cannot smash the strong shell of an adult dog whelk, but juveniles are vulnerable to attack from many predatory species. Eider Ducks and various other birds simply swallow the entire body with its shell, while oystercatchers and various crustaceans are often capable of crushing or breaking the shells. In the winter they endure more predation from Purple Sandpipers and similar wading birds, but in the summer crabs represent a greater threat. In general, the dog whelk can be thought of as being vulnerable to birds when emersed, and to crabs when immersed.

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The Dog Whelk (Nucella lapillus), can use its modified mouth to bore into molluscs. It can squirt a paralyzing chemical and digestive enzymes to help break the mollusc down. The resulting'soup' is then sucked out with a siphon. It can grow up to 4cm long.

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Video to watch with headphones

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Rocky Shore Habitat for OSS 3-5, Clip #3b for Session 2.2

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Abiotic Factors affecting the organisms in the Rocky shore

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Abiotic Factors affecting the organisms in the Rocky shore

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FSC (Field Studies Council) - Bringing Environmental Understanding to All

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The FSC (Field Studies Council) is an educational charity bringing environmental understanding to all.

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On land, the most important environmental conditions affecting organisms are rainfall and temperature. In our oceans, there are a number of environmental conditions that affect the growth, survival and productivity of marine organisms. These include light availability, oxygen levels, water movement, salinity, density and pH. These conditions often vary from habitat to habitat and will either support or limit the life processes of the marine organisms living there.

Light

On land, most photosynthesis occurs at or just above ground level, and there is no easily visible change in light as altitude increases. Things are quite different in the sea! Photosynthesis can only occur when enough light penetrates down the water column. This area is called the photic zone and varies from a few metres to as deep as 150 metres in some places.

The amount of light that can penetrate the surface is limited by a number of factors. For example, rays of light that approach at a low angle (at sunrise and sunset) are immediately reflected off the surface. Particles of organic matter and sediments from land also affect how much light is absorbed. All primary productivity occurs in the photic zone, and as a result, about 90% of all marine life lives in this upper zone.

Oxygen

Just as it is on land, oxygen is a very important gas in the ocean because of its role in the life processes of marine organisms. Dissolved oxygen in seawater comes from mixing (where the surface meets the atmosphere) and as a byproduct of photosynthesis. As a result, the most oxygen-rich water is found near the surface, so this is where the majority of marine organisms live.

Nature of science

Oxygen consistently makes up about 21% of the air that we breathe on land. However, the amount of dissolved oxygen in seawater varies considerably with temperature and salinity. (As temperature and salinity increase, the amount of dissolved oxygen decreases.)

Oxygen availability in the sea can also be affected by human activities on land. For example, nutrient run-off from farmland can cause rapid growth of phytoplankton resulting in phytoplankton 'blooms'. When these large numbers of organisms die, the sharp increase in decomposition depletes oxygen levels. In some cases, this can result in the death of large numbers of other organisms such as fish.

Movement of water

Movement of water, in the form of waves, tides and currents, plays an import role in our oceans and impacts on all marine organisms.

Waves are caused by wind acting on the surface of the sea. However, they impact on life beneath the surface, too. For example, a wave that is 2 metres high above the surface may be felt up to 6 metres below the surface. Waves can be very destructive; however, they also cleanse organisms and help to increase oxygen availability.

Tides are caused by the interaction of the forces of the sun and moon; in most places, tides occur twice daily. Tides have the biggest impact on marine organisms that live on coastlines. For example, these organisms need to adapt in order to resist drying out and to survive daily changes in temperature and salinity, and exposure to land-based predators at low tide.

Currents are caused by wind, tides and the global circulation of water. Currents play an important role in moving water between the poles and the tropics. Currents also move food and nutrients from the coast further out into the sea. Many organisms also rely on currents to transport their eggs and larvae.

Salinity

The salinity (or saltiness) of seawater varies considerably throughout the world's oceans. Although most seawater has a salinity of approximately 3-4%, it can reach up to almost 40% in some areas. In estuaries, salinity is typically low, as there is regular mixing with a freshwater source, such as a river. Salinity is typically highest in isolated bodies of seawater where the evaporation rates are high and precipitation rates are low.

Marine animals are adapted to keep their body salts at a constant level, so that they don't interfere with the metabolism within cells, but significant changes in salinity can cause problems for some. For example, some marine animals are described as stenohaline, which means they can't cope with large salinity fluctuations; others are euryhaline and can tolerate a wide range of salinities.

Density

Seawater is more than 800 times denser than air. This high density is related to salinity and temperature and means that objects that might sink in freshwater are able to float in seawater. This has a big effect on life in the sea. For example, the marine ecosystem has communities of plankton - vast numbers of floating organisms that are kept perpetually afloat due to the density of seawater. It also helps explain why marine animals can grow to be so much bigger than the largest animals on land.

pH

pH is a measure of the acidity or alkalinity of a solution. Pure water is said to be neutral. The pH of seawater is about 8, but this varies slightly throughout the world. There is scientific evidence that suggests that the pH in our oceans is decreasing and therefore becoming more acidic. This could have significant impacts on life in the sea. For example, many marine species rely on calcium carbonate to build a shell or skeleton.

One of the effects of increasing acidity is a reduction in the availability of carbonate. This means that any animal that produces a calcium carbonate skeleton will find it much more difficult to do so. Organisms could grow more slowly, their shells could become thinner or they might dispense with shells altogether. It is difficult to predict the overall impact on the marine ecosystem, but many scientists fear that ocean acidification has the potential to decrease marine biodiversity on a very large scale.

Published 8 October 2009

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Environmental conditions affecting the sea

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On land, the most important environmental conditions affecting organisms are rainfall and temperature. In our oceans, there are a number of environmental conditions that affect the growth, survival and productivity of marine organisms. These include light availability, oxygen levels, water movement, salinity, density and pH.

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Choose any 5 + 1 algae

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Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

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Work to do for the week beginning the 4th March

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Work to do for the week beginning the 4th March

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1. Click on the Foods chains icon at the bottom of this column & READ the material called revise.
2. Listen to the activity with earphones
3. Try the test.

Then look at the Prezi on Interrelationships on the rocky shore.

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A shows what eats what in a particular habitat. It shows the flow of energy and materials from one organism to the next, beginning with a .

In the example, grass seeds are eaten by voles, and voles are eaten by barn owls. The arrows between each organism in the chain always point in the direction of energy flow from the food to the feeder.

The is the ultimate source of energy for most communities of living things. Green plants are usually the producers in a food chain.

are organisms that make their own organic nutrients (food) - usually using energy from sunlight. Green plants make their food by . The other organisms in a food chain are , because they all get their energy by consuming other organisms.

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BBC Bitesize - GCSE Biology (Single Science) - Food chains - Revision 1

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A shows what eats what in a particular habitat. It shows the flow of energy and materials from one organism to the next, beginning with a . In the example, grass seeds are eaten by voles, and voles are eaten by barn owls.

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Look at this Prezi to show feeding relationships in the Rocky shore

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Organisms in NZ rocky shore ecosystem Conclusion Autotrophs When we use numbers of organisms (i.e. population)for the pyramids, we would get pyramid on the left hand side. Number of producers is small compared to primary consumers and secondary consumers because a single seaweed

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More information about the Rocky shore and the organisms

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More information about the Rocky shore and the organisms

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This diagram shows the typical distribution of common organisms on the rocky coasts of New Zealand. Most species are adapted to a specific zone.

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Ask your teacher for a hard copy of the NZ Rocky shore resources

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Year 12 Bio book
Page 23 look at special skills
Do Q2 on page 24

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Easy to understand information on the Rocky shore

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Easy to understand information on the Rocky shore

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This article describes the habitat of rocky shores. It is one of the habitat sub-categories within the section dealing with biodiversity of marine habitats and ecosystems. It gives an overview about the type of biota that lives there, the problems and adaptations the habitat is facing with and the importance of it in the marine environment.

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Being able to adapt is a matter of life or death. In a perfect world, organisms would not need to adapt. However, changes to the environment and food web mean that organisms need to move, if they can, adapt or become extinct.

Adaptation

Adaptation is a trait that enables an organism to live in its environment. Adaption occurs in three ways:

Behavioural adaptation relates to the behaviour of the organism. For example, fish swim in schools or large numbers to protect members of the group from predators.

Structural adaptation relates to the organism's physical features. For example, many bivalve (two shells) molluscs have specific structures, such as siphons, gills and cilia that allow them to filter out food.

Physiological adaptation relates to how an organism's metabolism works. For example, some soft-bodied sea animals excrete chemicals as a defence mechanism.

Behavioural adaptation happens more quickly than structural or physiological adaptation. The more intelligent an animal is, the faster it can learn to make behavioural changes in order to survive. However, structural and physiological adaptations require genetic change, which can only occur through mutation or other gene changes over several generations. The article Marine organisms and adaptations provides additional information about these categories.

The following are some examples of adaptations of organisms within habitats found in marine environments like the Bay of Plenty.

Adapting to estuaries

Estuaries are where freshwater from the land mixes with saltwater from the sea. Consequently, the salinity levels of the water change over the tidal cycle. Plants and animals living in estuaries must be able to respond quickly to drastic changes in salinity. Organisms that are capable of dealing with varying salinities are euryhaline (like mangroves), and organisms that can only deal with small changes in salinity are stenohaline. Stenohaline animals rely on behavioural adaptations such as moving out of the area, burrowing in the sand and closing their shells or physiological adaptations such as excreting excess salts. Worms, molluscs and fish can produce mucus or slime to cover sensitive body parts.

Some marine animals have evolved interesting ways to survive the challenges in estuaries. For example, mud snails (tītiko) are like gardeners. They suck in and excrete mud, ploughing it up and improving its properties so that plants grow more easily. These are the plants the snails then feed on.

Marine bristleworms or polychaetes use their fine bristles for swimming and holding themselves in their burrows. Some make 'shells' for protection. These shells are tubes made of sand and shell segments held together with a sticky secretion.

Adapting to beaches

Beach habitats are an extremely dynamic environment where sand, water and air are always in motion. Surf beaches are particularly dynamic. The burrowing of animals must be rapid and powerful so that the animals are not swept away by incoming waves and swash (turbulent water movement). Desiccation (drying out) is not a concern to these animals because they can retreat into the substratum (well below the initial layer of sand) or below the water table.

Bivalves such as tuatua tend to live along the beaches. To avoid predation, they can burrow deeply into the sand or migrate on the tide to a different area.

Paddle crabs use the paddles on their rear legs to burrow into the sand for protection, with only their eyes and antennae protruding. They also use their paddles for swimming. They forage for food at night, often predating on tuatua and other shellfish.

Adapting to rocky shores

Desiccation threatens animals living in intertidal zones on the rocky shore. Some adaptive features include migration to an underwater area (if they are mobile), restricting activities (reduced metabolism) and attaching more firmly to the rocks along with resistant shells and the ability to retain water.

Molluscs on the rocky shore are mostly univalved (one shell). They cannot burrow into sand like the bivalves for safety so they have very strong shells with an operculum (trapdoor attached to the foot muscle). Limpets are a good example of this. They are particularly well adapted for life on rocky surfaces. Every limpet has a 'home' spot on a rock. This is the place they stay when the tide is out. On soft rock, the limpet grinds it with its shell to make an exact fit. On hard rock, the shell is ground down to fit the rock's shape. The tight fit allows the limpet to trap some water inside its shell to stop it drying out. It has a strong foot muscle that grips onto the rock - making it difficult for birds to prise it off.

Dog whelks are active predators. They have special drilling mouth parts used to bore through the shells of other molluscs such as limpets and barnacles. They can also produce a shell-dissolving acid to help them reach inside the shell. They then suck up the flesh.

Activity idea

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Being able to adapt is a matter of life or death. In a perfect world, organisms would not need to adapt. However, changes to the environment and food web mean that organisms need to move, if they can, adapt or become extinct.

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Biodiversity is short for biological diversity. It refers to the number and variety of living things (animals, plants or microorganisms) found within a particular area. There are complex relationships between this variety of life. Marine biodiversity specifically refers to the variety of life in coastal and ocean environments.

Biodiversity includes:

genetic diversity - the different genetic make-up among individuals of one species

species diversity - the different species within a habitat such as the birds, worms, fish, bacteria, insects and molluscs that live within an estuary

ecological diversity - the different ecosystem types (estuaries, oceans, forests, wetlands, grasslands, streams) and the communities within them.

Marine biodiversity

Marine species make up almost one-third of New Zealand's total number of described native species. However, about seven new marine species are identified each fortnight - many more are yet to be discovered. Scientists estimate there could be as much as 80% of New Zealand's biodiversity living in the sea.

A species inventory for New Zealand was developed over the last decade through a project called Species 2000: New Zealand. This project formally identified about 12,000 marine species in New Zealand's waters, with another 3550 known but not yet described. It is estimated that, at the present rate of description, it would take another 100 years to describe the remaining marine species.

Described species include:

seabirds

marine mammals

fish

molluscs (snails, shellfish and squid)

sponges

echinoderms (kina, starfish)

seaweeds

microalgae.

Examples of all of these are found in various Bay of Plenty habitats.

Life in the estuaries

The soft estuary bottom (consisting of sand and mud, including sediment carried down by rivers) supports a range of burrowing fauna such as worms, cockles and pipi. Most of these animals feed on accumulated debris and bacteria and algae films on the mud surface. Estuaries are ideal refuges for juvenile fish of many species and wading birds in search of fish and crustacea.

Life in the beach zone

Bay of Plenty beach zones support abundant species such as shellfish - pipi, tuatua, biscuit shell, dog cockle and triangle shell. Sandhoppers can often be found jumping around in the debris left by an outgoing tide, called the wrack line. Terns and gulls often pick through debris. Pieces of driftwood often contain oyster borers and other insects. Fragments of dead seaweed such as sea lettuce and kelp are also common in this area.

Life on the rocky shore

The rocky shores support a huge diversity of life. Life here is not easy. Salinity, water, wave action, competition and predation are all factors affecting survival chances of life on the rocky shore. However, examples of many marine organism groups can be found there. Some examples are sea anemone, kina, sea cucumber, sea slugs, sea stars, pāua, crabs, chitons, sponges, worms, shrimp, barnacles, sea squirts, seaweeds, crayfish, octopus, fish, oysters and mussels.

Life around the offshore islands

These mostly volcanic rocky shores exposed to warm ocean currents support a unique diversity of subtropical marine life. In addition to species found on most New Zealand rocky shores, these habitats include long-finned boarfish, clown toado, crimson cleanerfish, the colourful splendid perch, Sandagers wrasse, copper moki and, in the summer, turtles.

The importance of biodiversity

New Zealand's marine biodiversity is ecologically important because it is unique and of international importance - many of our species are not found anywhere else on Earth. Biodiversity also has intrinsic value - the value of the variety of life itself - and creates ecosystems that allow organisms to flourish in an interdependent web of life. Some of these species have commercial value to us as food and sources of potential medicines. Our relatively unspoiled marine environment also has economic value for tourism and our fishing industry. Finally, of cultural significance is that Māori have a special affinity with the oceans in a non-material way, and this is recognised in the Treaty of Waitangi.

Nature of science

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Biodiversity is short for biological diversity. It refers to the number and variety of living things (animals, plants or microorganisms) found within a particular area. There are complex relationships between this variety of life. Marine biodiversity specifically refers to the variety of life in coastal and ocean environments.