Marine Reptiles, Birds and Mammals Vertebrates! Invaded the land and are descendants from the bony fish and were able to withstand the conditions on the land.! They evolved two sets of limbs (even snakes) and are called tetrapods, meaning having four appendages or feet.! Three things needed to survive on land were:! 1. Have lungs and breathe air! 2. Have a body resistant to drying out.! 3. Have eggs that can survive on land and not dry out. Amphibians! Amphibians really never solved the problem. They need to keep their skin moist and must lay their eggs in the water. Any animal that lays eggs is considered oviparous. Tadpole in Water Reptiles Eggs! Reptiles evolved from amphibians and were the dominant land vertebrate for millions of years. Their skin and their eggs have the ability not to dry out on land.! 1
Birds and Mammals! Birds and mammals continued to evolve from the reptiles. Marine Reptiles! There are about 6000 species of reptiles including snakes, turtles and crocodiles. The eggs have a leathery shell that prevents it from drying out. Reptiles are ectotherms, or cold blooded which means that when the temperature is cold they are sluggish and when they are warm they are more active. Sea Turtles! Sea turtles are reptiles enclosed in an armor-like shell that is fused to the backbone. Tortoises and turtles can retract their head, but sea turtles cannot. Sea turtles usually only leave the water to lay eggs. Travels of the Sea Turtle! Sea turtles have the ability to travel long distances to eat and return to the same breeding ground year after year. Laying Eggs Leatherback Turtle! There are 8 species of sea turtles that feed primarily on seagrasses and seaweed. Some have been known to eat jellyfish, even the super poisonous box jellyfish. The largest sea turtle is the leatherback, which can reach up to 7 feet in length. 2
Sea Turtles Mating! Copulating pairs are often seen offshore but only the females venture ashore to lay the eggs. The females will dig a hole using their flippers and lay about 100-160 large leathery eggs and then bury them. Eggs to Turtles! The eggs hatch in about 60 days and the tiny babies make it back to the water. The eggs and the young are very venerable to predation by dogs, birds, crabs, fish and many other animals. Sea Snakes! Sea snakes have about 55 species and found in tropical oceans. The tail is flattened into a paddle shape and can grow up to 4 feet in length. They are ovoviviparous, which means the mother keeps the fertilized eggs that will hatch inside of her body. They do not need to return to land to breed, but some do. Are they a danger to people?! Sea snakes are venomous and are carnivores and feed primarily on fish and fish eggs. People that die from their bite either step on them or get bit while cleaning out their fishing nets. The are endangered and are being overexploited for their skin and some are near extinction. Sea Snakes Salt Water Crocodile! Another sea reptile is the saltwater crocodile which inhabit mangrove swamps and estuaries in eastern Indian Ocean, Australia, and other Pacific Islands. 3
Big Crocs! Some will venture out into the open ocean and can grow to be about 20 feet and the largest one on record was 28 feet long. Sea Birds! Birds have an advantage over reptiles because they can fly and are endotherms, which means they are warm blooded, and their body temperature is not regulated by the environment. Because of this fact, they can live in a variety of water temperatures. Birds have a waterproofing oil glands near their tail and use their beaks to spread the oil over their feathers. Sea Birds! Seabirds are those birds that spend most of lives at sea. They nest on land but feed primarily in the water. Seabirds make up only about 3 % of all bird species but are distributed from pole to pole. Most eat fish, squid and small invertebrates. Penguins! Penguins are seabirds most fully adapted for life at sea. The wings are flightless but are good swimmers. Their bones are denser to help in diving. 4
Where are Penguins Found?! They are great swimmers and their eyes are adapted for underwater vision but on land, their eyesight is poor and they are clumsy. They can withstand the cold weather because of a layer of fat under the skin. 17 of the 18 species live in the southern hemisphere near Antarctica, one species lives in the Galapagos Islands near the equator. Pairing and Mating! Most penguins will migrate to feed and will return to land or ice to lay the eggs. Emperor penguins are season long pairs and the male guards a single egg during the dark winter in Antarctica while the females go out to eat. The egg is laid in the winter so the newborn can be born in the warmer summer. Large Groups to Mate One Egg per Pair Pelicans Sea Gulls! Pelicans can fly and have a specially adapted pouch in the beak to catch fish. Pelicans live in large colonies along the coast.! Seagulls are widespread and are predators and are scavengers and are happy to eat anything they can find. 5
Marine Mammals Marine Mammals! Mammals like birds are endotherms and for the most part are viviparous. The embryo receives nutrients through the placenta and the newborn is fed with milk produced in the mother s mammary glands. The brain is the largest and most complex of all of the other marine animals. Seals, Sea Lions and Walruses! Seals, sea lions and walruses that can swim but need to rest and breed on land. Most seals will live in cool to cold water and have a thick layer of blubber under the skin. It serves three purposes; 1. Reserve for food. 2. Help in buoyancy. 3. Helps to keep in the heat. Sea Lions vs. Seals! Sea lions are similar to seals with the exception of their ears. Sea lions have external ears while seals have internal ears. Which one is the seal? Walrus! The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-arctic seas of the Northern Hemisphere. The walrus is immediately recognized by its prominent tusks, whiskers and great bulk. Adult males can weigh up to 3,700 pounds. 6
Sea Otters! Sea otters are the smallest members of the marine mammals. They are usually between 60-80 pounds and are insulated with air trapped in their dense fur. They are intelligent and playful. They spend most of their life in the water and feed on sea urchins, mussels, crabs and other marine invertebrates. 7