facts about dolphins

[dolphin]

Have you got any facts about dolphins? I saw some similar threads on other parts of this site and so thought I'd ask as well There must be tons of facts about dolphins because they're such incredible animals, so let's hear them

[karlabb]

aren't they descendants of land animals like cows and sheep? can never remeber which ones became dolphins and which became porpoises

[Spaz]

Well, I know that dolphins sometimes gang up on other animals, such as sharks, to drive them away. Also, although we see dolphins and nice, gentle creatures, sometimes dolphins will gang up on the smaller dolphins . Why? I'm not quite sure, but I remember watching something about them on Animal Planet.

Also, they are related to whales.

[frostfire]

Originally Posted by karlabb

aren't they descendants of land animals like cows and sheep? can never remeber which ones became dolphins and which became porpoises

Despite a lot of research the precise origins of modern cetaceans remains uncertain. It is generally believed though, thanks to DNA research and fossils, that whales and dolphins developed from land mammals about 70 million years ago around the ancient Tethys Sea. Some experts believe that they had develloped from Creodonts, -medium sized and large headed mammals, which are also the ancestors of the modern day carnivores and hoofed animals.
Though there is no evidence, it is believed, that for many millions of years the ancestors of whales and dolphins were simalair to hippos and that they mainly ate crustacians and molluscs.

[frostfire]

2007 was the year of the dolphin and has been extended into 2008!

Year of the Dolphin *—* Home

Just wondering if anybody noticed any of their happenings or knows of events coming up?

[paul m]

It seems that there was a paradox (for engineers) that dolphins shouldn't be able to swim (in the same way that bumble bees shouldn't be able to fly) but that's all cleared up now:
BBC NEWS | Science & Environment | Mystery of dolphins' speed solved
It's all a matter of aerodynamics - shoud that be aquadynamics?

[Gary Winnick]

Yeah I agree with you Dolphin is really incredible animal. Some time they love peoples very much and some time they attack on people.

[gissele]

I too agree with Dolphins are really incredible animals.
-The average botllenose dolphin brain weighs 1500-1600 grams.
-dolphins can swim 5 to 12 kilometers per hour, although they can reach up to 32 km/h.

[paul m]

A sad fact: dolphins seem about to become extinct on the Mekong - due to pollution:
BBC NEWS | Asia-Pacific | Mekong dolphins 'almost extinct'

[paul m]

Well, cetaceans (all the whales, including porpoises and dolphins) emerged from early land mammals. It's hazarded that a mammal adapted to living beside the sea (swimming-hunting but not able to live in the sea full time) which gradually evolved to aquatic life.
A good projection is at: Douglas J. Futuyma, "Cetacea Evolution," Evolutionary Biology, 1998

Originally Posted by karlabb

aren't they descendants of land animals like cows and sheep? can never remeber which ones became dolphins and which became porpoises

[paul m]

Another dolphin species under threat:
BBC NEWS | Science & Environment | Swine flu puts porpoise on brink
A sad example of how human misfortunes can have a knock-on effect to other species ....