Dolphins are mammals closely related to whales. Bottlenose dolphins are carnivores that can be about 14 feet long and can weigh over 1,000 lbs. Bottlenose dolphins eat bottom-dwelling fish, shrimp and squid. They come to the surface of the water to breathe and use squeaks and whistles to communicate with each other. The smallest dolphins are Maui's dolphins, which are around 4 feet long and weigh no more than 90 lbs. The largest dolphins are orcas, which are called killer whales even though they're technically dolphins. Orcas can grow as large as 32 feet long and weigh 8 to 9 tons.
The shark dates back over 420 million years. There are 440 species of sharks, and very few of them are big enough to threaten humans. Sharks have a full skeleton made of the rigid material cartilage, which is also found in humans as connective tissue. Sharks are carnivores and eat other fish, crustaceans, mollusks and marine mammals. The most famous shark, the great white, can weigh up to 5,000 lbs and usually grow as long as 15 feet.
Jellyfish are simple-bodied invertebrates found in deep ocean water and along coastlines. Jellyfish eat fish, shrimp, plants, crabs and other species of jellyfish. Jellyfish use their tentacles to sting their prey and paralyze them before they devour them. Jellyfish do not have backbones. Jellyfish can be clear, but can also be luminescent colors of pink, yellow, blue and purple.
Sea otters are members of the weasel family and are the second smallest marine mammal behind the Commerson's dolphin. Sea otters are very similar to seals but there some major physical differences. Seals keep warm with their blubber, have flippers and have no visible earflaps. Sea otters have very thick fur, have paws instead of flippers, and they do have earflaps. Sea otters live in shallow coastal waters off the northern Pacific Ocean where they dive for sea urchins, abalone, mussels, clams, crabs and snails. Sea otters can weigh up to 100 lbs.
Whales are mammals that breathe air through a blowhole on top of their heads. Whales need air to survive, but can stay underwater for as long as 90 minutes. There are Baleen Whales that eat krill and plankton, and Toothed Whales that eat fish and small mammals such as seals. Some whales, like blue whales and humpback whales, make singing and clicking noises as a form of communication.
Sea turtles can be yellow, green or black. They can weigh between 80 to 3,000 lbs depending on the species. Sea Turtles are very sensitive to sound. They're colorblind, but they have keen senses of smell. Sea Turtles eat such things as jellyfish, seaweed, crabs, shrimp, snails, algae and mollusks.