Arctic Sea Ice and the Food Web Page 1 Teacher Zone nature.ca/education See the associated lesson plan at

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

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

The Basis of the Food Web The basis of the food web in oceans depends primarily on microscopic plants called 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

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. Page 5 Northern Krill (Meganyctiphanes norvegica). Uwe Kils © Uwe Kils

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

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

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

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

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

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

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

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

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

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

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

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

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 Canadian Museum of Nature Page 17 Teacher Zone nature.ca/education

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. Page 18 Teacher Zone nature.ca/education Arctic Sea ice. Stewart Canadian Museum of Nature