Order - Cetacea
Have you ever heard of cetaceans? Well if you have not, let me ask you this, "have you ever heard of dolphins, whales, or porpoises?" I have always liked cetaceans because they are very amazing and smart animals! Cetaceans live all over the world, from the warm areas of the Mexican Coasts to the icy and cold seas of the North. Most whales migrate all over the world according to the season.
Bryde whales don’t usually migrate far; they like to stay in warm waters year round. Pacific Gray Whales show a tropical pattern. In early winter, perhaps in response to hormonal changes initiated by shorter days, they move south to breed in warm shallow lagoons along the Mexican coast. In February they migrate north to feed along the coasts of Alaska and the Beaufort Sea. Baleen Whales make essentially north/south migrations between cold water feeding areas for summer and temperate or tropical breeding areas for winter.
Reproduction is very important with any animal group. Bottle Nosed dolphins can produce up to one calf every 2 years but they usually have one every three years. It takes 12 months for a calf to fully develop in its mother’s womb, when it is born (tail first) it nurses from its mother for about 4 years and stays with its mother for up to 6 years. In this time it learns all about feeding techniques, social interaction, and group foraging.
It is very hard for a mother dolphin to take care of her calf so she has a friend or sister help. The dolphin who helps the mother is called the “auntie” (can be a male or female). It is the only other dolphin allowed near the baby calf. Whales and dolphins show dramatic adaptations for life underwater. Changes in almost every body system make them quite unlike other mammals. They are able to survive because of these adaptations.
Dolphins have large brains compared to the size of their bodies. This shows that they are very smart. A dolphin has a long nose that can help it kill sharks. Their heart beats slower while diving and their blood travels from other parts of their body to their brain, heart, and lungs. Their muscles have a special protein called Myoglobin which helps the dolphin store oxygen. Blubber (fat) helps the dolphin stay warm in cold water. Dolphins only have one set of teeth; they use their teeth to catch fish. Dolphins have large brains that help them to think of good ways to do anything under the ocean.
Different types of cetaceans feed on different things. The baleen whale uses a technique called “filter feeding”. Their “teeth” are long brush like bristles. When they take a big mouthful of water they can filter out the small krill, shrimp or even plankton and eat them. Right Whales feed a little differently, moving slowly at or near the surface, and forcing a stream of water across their very long baleen plates to skim off food. Most whales eat small fish or krill and sometimes even other small organisms (shrimp, plankton, ect.) Feeding with toothed whales and dolphins is a little different than with baleen whales. Toothed whales and dolphins are called odondocetes; odondocetes hunt and eat relatively large single prey.
Most dolphins feed on middle level fish, squid, and shrimp but in shallow seas they may eat bottom dwelling and reef organisms. Dolphins, whales, and porpoises play an important part in taking care of the oceans. They are amazing creatures! Dolphins help in keeping the fish (including shark) population down. This is important in keeping the ocean balanced because if you have too many of one creature, the ocean would be full of krill, shrimp, plankton, (ect.) Cetaceans are just a part of the ocean, keeping it balanced just like every other part. Over the millions of years in existence, cetaceans have had to think of strategies to deal with the attacks of their predators. The natural predators of cetaceans are orcas and sharks, while in the Arctic Polar Bears may prey on stranded Belugas.
The most common defensive strategy for cetaceans is to form a large group rather than an individual, sometimes groups of oceanic dolphins even number in the thousands! Different strategies are used when whales are under attack from predators, they may flee or if they are slow swimmers or have young they might stay and fight. All in all, cetaceans are very smart and complex creatures who have learned how to survive in the ocean. Looking back, you can see that they have spent millions of years figuring out ways to eat (not to mention what and what not to eat) and what creatures to avoid. I think that cetaceans are very important and that everybody can learn something from them.
Author: Serafina G.
Published: April 2006
http://www.sfwmd.gov/org/wrp/wrp_ce/2_wrp_ce_info/photos/hires/dolphin.jpg http://www.coastalconservancy.ca.gov/coast&ocean/FALL2002/graphics/fiveart/dolphins.jpg http://swfsc.nmfs.noaa.gov/PRD/PROGRAMS/POP-ID/case/killerwhales.html