Arctic Sea Ice and the Food Web

1. Arctic Sea Ice and the Food Web See the associated lesson plan at http://nature.ca/education/cls/lp/lpasi_e.cfm Page 1 Teacher Zone nature.ca/education

2. Arctic Sea Ice and the Food Web Sea ice plays an important role in the food web of the Arctic marine ecosystem. In this presentation, you will encounter a variety of species that are part of this ecosystem. Arctic sea ice in Resolute Bay. André Martel © Canadian Museum of Nature Page 2 Teacher Zone nature.ca/education

3. Sea-Ice Core • The underside of Arctic sea ice provides habitat for a community of algae and associated microscopic life known as sympagic organisms. • They are an important food source for other marine animals higher up in the food web. • In this image, you can see a colony of diatoms (a type of algae) on the bottom of a core sample of Arctic sea ice. Diatoms in sea ice core. Michel Poulin © Canadian Museum of Nature Page 3 Teacher Zone nature.ca/education

4. The Basis of the Food Web • The basis of the food web in oceans depends primarily on microscopic plantscalled phytoplankton, which usually live in the water. • In the Arctic, phytoplankton are also found in and on the sea ice. • Phytoplankton use the energy of the sun to make carbohydrates using the process of photosynthesis. Diatoms (Trigonium arcticum) viewed through a microscope. Kathy Conlan © Canadian Museum of Nature Page 4 Teacher Zone nature.ca/education

5. Zooplankton • This provides a food supply for a group of tiny animals known as zooplankton, which live in close association with, or even inside, the sea ice. • The zooplankton include various microscopic animals as well as small crustaceans such as amphipods, copepods and krill. Northern Krill (Meganyctiphanes norvegica). Uwe Kils © Uwe Kils Page 5

6. Amphipods • Amphipods are small, shrimp-like crustaceans. • Amphipods are eaten by fish such as Capelin and Arctic Cod, which are very important in the diet of other fish, marine mammals and seabirds. • Some seabirds, such as the Arctic Tern, also feed on amphipods, as do young seals. Amphipod (Anonyx sp.). Kathy Conlan © Canadian Museum of Nature Page 6 Teacher Zone nature.ca/education

7. Isopods • Isopods are a very diverse group of crustaceans. The group includes sowbugs, which can often be seen in basements or gardens. • The isopods that live in the Arctic Ocean are mostly carnivorous. They feed on dead whales, fish and squid. • Isopods may also be active predators of slow-moving prey, such as sea cucumbers, sponges, radiolarians, nematodes and other animals that live on the ocean floor. Isopod (Arcturus baffini). Kathy Conlan © Canadian Museum of Nature Page 5 Teacher Zone nature.ca/education

8. Cockles • The cockle is a bivalve (an animal with a shell made up of two halves). • Bivalves include clams, scallops, mussels and oysters. • Arctic cockles are preyed upon by fish, walruses, bearded seals and several duck species. Cockle (Serripes groenlandicus). Kathy Conlan © Canadian Museum of Nature Page 7 Teacher Zone nature.ca/education

9. Nudibranchs • Nudibranchs are gastropods. They are commonly referred to as sea slugs. • A nudibranch is carnivore that lives on the sea floor, and, depending on the group, feeds on hydroids, sponges, anemones, bryozoans and other organisms. Nudibranch (Dendronotus frondosus). Kathy Conlan © Canadian Museum of Nature Page 8 Teacher Zone nature.ca/education

10. Sea Cucumbers • Sea cucumbers are animals in the phylum Echinodermata. • They are generally scavengers. They use their tube feet to trap food particles, such as dead and decaying matter, from the sea floor sediment. • Many also use their branchial tree to trap particles suspended in the water. Sea cucumber (Cucumaria). Kathy Conlan © Canadian Museum of Nature Page 9 Teacher Zone nature.ca/education

11. Sea Anemones • Sea anemones are animals in the phylum Cnidaria. • They usually remain attached to hard surfaces, such as shells or rocks, but some of them burrow into the sea floor. Sea anemone (Hormathia nodosa). Kathy Conlan © Canadian Museum of Nature Page 10 Teacher Zone nature.ca/education

12. Sea Urchins • Sea urchin are another group of animals in the phylum Echinodermata. • They usually live on hard substrates, and feed by scraping off algae and encrusting animals with their five teeth. • Their teeth are located in a complex organ on the underside of their shell that is called an Aristotle’s lantern. Sea urchin (Strongylocentrotus pallidus). Kathy Conlan © Canadian Museum of Nature Page 11 Teacher Zone nature.ca/education

13. Sea Stars • Most sea stars are carnivores whose favourite food are bivalves. • They have a unique feeding method: they use their tube feet to pry open the two halves of a bivalve, and then they insert their stomach inside it! • Their stomach then releases enzymes that slowly digest the animal within its own shell. Sea star (Crossaster papposus). Kathy Conlan © Canadian Museum of Nature Page 12 Teacher Zone nature.ca/education

14. Arctic Cod • Arctic Cod are fish that eat mainly crustaceans, such as shrimp, amphipods and copepods. • Arctic Cod are eaten by a variety of other large fish, as well as many seabirds and most Arctic marine mammals. • They are the link in the food web between small amphipods and higher vertebrates. Arctic Cod (Boreogadus saida). Kathy Conlan © Canadian Museum of Nature Page 13 Teacher Zone nature.ca/education

15. Walrus • Walruses prefer to eat molluscs (mainly bivalves such as clams and mussels), which they suck from the shells. • They also consume many other kinds of invertebrates including worms, gastropods, cephalopods, crustaceans, sea cucumbers and other soft-bodied animals. Walrus (Odobenus rosmarus). Stewart MacDonald © Canadian Museum of Nature Page 14 Teacher Zone nature.ca/education

16. Ringed Seal • Ringed seals are the most abundant seal species in the Arctic. • They use the ice for breeding, moulting and resting. They rarely, if ever, move onto land. • Ringed seals have a varied diet that comprises primarily shrimp-like crustaceans and small fish such as Arctic Cod. Ringed seal (Pusa hispida). ©iStockphoto.com/Zvozdochka Page 15 Teacher Zone nature.ca/education

17. Beluga • Belugas are commonly found in ice-covered waters. They rely on open water at ice edges, leads and polynyas as places to surface for breathing. • They feed on crustaceans and small fish such as Arctic Cod. Beluga (Delphinapterus leucas).Buchan/Shutterstock.com Page 16 Teacher Zone nature.ca/education

18. Polar Bear • The polar bear is dependent on sea ice for most of its needs, and as a result, is often regarded as a marine mammal. • A polar bear’s diet consists mainly of ringed and bearded seals. • Polar bears also occasionally feed on whales and young walruses. Polar bear (Ursus maritimus). Stewart MacDonald @ Canadian Museum of Nature Page 17 Teacher Zone nature.ca/education

19. Arctic Sea Ice and the Food Web The Arctic marine ecosystem is more fragile than more-complex ecosystems found further south. If one species is lost, there may be few or none that can take its place in the food web. Arctic Sea ice. Stewart MacDonald @ Canadian Museum of Nature Page 18 Teacher Zone nature.ca/education