Lesson 20: Vertebrates II Marine Biology

Classification Overview Common Vertebrates Phlyum Subphylum Chordata Vertebrata Classes Chondrichthyes Actinopterygii Reptilia Mammalia Vertebrates: Animals with a backbone We’ve been learning about marine life in the sub- phylum vertebrata What are some common features of this sub-phylum? Today we’ll conclude our survey of life in the sea by taking a look at the class mammalia 2

Warm-blooded animals Marine mammals are warm-blooded: they keep a constant internal temperature They also share other characteristics: – Give birth to live offspring – Hair on some part of the body – Mammary glands to provide milk to young Classification Overview Common Mammalian Orders Sub-PhlyumClass Vertebrata Mammalia Orders Pinnipedia – Seals, Sea Lions, Walrus Cetacea – Dolphins, Whales Sirenia – Mantees 3

Heat loss is high in the ocean Heat loss in the water is faster than in the air, even at the same temperature So how do marine mammals maintain their body temperatures? – Countercurrent heat exchange - Insulation (blubber, fur) - Behavioral strategies (coming to the surface to get warm) - High metabolism Heat from blood traveling through the arteries is transferred to blood traveling back to the body core from the extremities, so that heat isn’t lost to the environment 4

Pinnipeds: Animals with “fin feet” Order Pinnipedia refers to mammals with large fin- like flippers including sea lions, seals and walruses Pinnipeds come onto the shore to breed and, like other mammals, give birth to live young Do you know the difference between a seal and a sea lion? 5

Seals and sea lions Seals lack ear flaps and have rear flippers that point backward Because they can’t rotate their flippers, they don’t move very well out of water Sea lions have ear flaps Sea lions can rotate their flippers forward and thus are more mobile out of water Steller Sea Lion Photo: NOAA Spotted Seal Photo: NOAA National Marine Mammal Laboratory ear flap 6

Order Cetacea: Whales, dolphins, and porpoises Cetaceans are highly adapted to life underwater They share several characteristics – No hind limbs – Muscular tail – Fish-like body form – Blowhole at the top of the head for breathing – Blubber (fat layers) to insulate the body 7

Baleen whales: Suborder Mysticeti Did you know that some whales don’t have teeth? Baleen whales trap food in their mouths using a broom-like filter that catches krill and small fish Many of the largest whales belong to this sub-order Photo: NOAA 8

Humpback whales are known for their complex songs Males use these songs to communicate and to court females Let’s meet some baleen whales Blue whales, shown above, can be up to 90ft long They are identified by their characteristic skin pigmentation Photos: NOAA 9

Toothed whales: Suborder Odontoceti Unlike the baleen whales, marine mammals in the suborder Odontoceti have teeth This suborder includes dolphins, orcas (killer whales) and the sperm whale These mammals use sound waves (echolocation) to help find their way underwater, to communicate and in some cases to hunt prey 10

Let’s meet some toothed whales The sperm whale primarily hunts deep ocean squid, including the giant squid, which can grow over 50 feet long Photo: NOAA Pacific white-sided dolphins (below) are very social mammals, usually traveling in groups of dolphins Photo: NOAA 11

Dolphins and porpoises Dolphins and porpoises are both toothed whales, but they are in separate families Dolphins (Delphinidae)Porpoises (Phocoenidae) Teeth are cone-shapedTeeth are flattened Beak-shaped snoutBlunt snout Hooked or curved dorsal finSmall, triangular dorsal fin Often seen at surfaceSeen only briefly at surface Photos: NOAA 12

Student activity In today’s activity, you will practice identifying marine mammals 13