Marine mammals: pinnipeds and cetaceans
Pinnipeds are large animals with a short neck and limbs turned into flippers; they hunt mainly in water and come out onto land or ice to rest and give birth. Seals, fur seals and the walrus belong to this order. On land they crawl, and the hind flippers mainly help swimming. The body is covered with short sparse fur, most seals have no outer ear, and they eat fish, molluscs and crustaceans. A female seal bears one pup on the ice; the pup has soft white fur that protects it from cold and hides it on the ice. The walrus has long canine tusks in the upper jaw. Fur seal numbers fell so much that hunting is restricted. Cetaceans have gone completely aquatic: they never come ashore, give birth in water, swim by the tail and front flippers, have no hind limbs and no outer ear. The blue whale is the biggest mammal: over 30 m long and more than 150 t. It is a toothless (baleen) whale: horny plates (baleen) hanging from the upper jaw strain small crustaceans from the water; it eats up to 2–4 t a day. Toothed whales include dolphins and sperm whales: their teeth are conical and all alike, only holding prey. A dolphin is up to about 3 m long, finds prey by ultrasound, has a complex brain, talks with sound signals and calls others to help a distressed friend. Whales and dolphins are mammals: they breathe by lungs, so they surface to take air, and they feed their young with milk. Hunting them is restricted or banned by international agreements. Safety: do not touch a marine animal stranded ashore – inform the proper service through adults; do not swim up to wild marine animals.
Venn diagram: write common and different features of pinnipeds and cetaceans (flipper, ear, birth place, breathing). Safety: do not cross barriers at the seashore or a zoo; do not feed animals or approach unseen; go into water with adults.