A porpoise is a small cetacean, belonging to the family Phocoenidae. They are related to both dolphins and whales. There are a few differences between dolphins and porpoises, although many people, including fisherman, identify small dolphins as porpoises. One difference between the two is that porpoises have flattened (spatulate) teeth that are distinct from the conical teeth of dolphins. Another difference is that porpoises are r-selected compared to dolphins, meaning that they have more offspring more quickly then dolphins. Porpoises are smaller in size and more stouter. Dolphins have bigger heads and beaks, while porpoises have small, round heads with a blunt jaw. Porpoises have spade-teeth and dolphins have conical teeth. They also have dorsal fins that are shaped like triangles. Porpoises have the ability to dive lengths up to 200m, but they perfer to hunt in shallower waters. They are predators of small fish, squid and crustaceans. They can be found in small groups, usually ten or less individuals. They are fast swimmers and have the ability of echolocation to find prey and group-coordination. Porpoises are not acrobatic like dolphins and when they swim up-side down, they tend to be looking for a mate. In some countries, porpoises are hunted for food or bait meat. A decline in porpoises numbers has occurred due to bycatch in fishing nets. One of the most endangered species is the Vaquita because it is mainly limited to the Gulf of California, a highly industrialized area.
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1 comment:
I like the second link.
Cathy
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