2007-03-05 09:44:39 · 8 answers · asked by circusgirl322 1 in Science & Mathematics ➔ Biology
Mammals have a LOT of characteristics in common. Specifically:
- vertebrates (they have a backbone)
- four-chambered heart
- have hair or fur
- specialized teeth, jaw hinged on skull
- three small bones in the ear
- produce milk
- blood cells without nucleii
- a neocortex region in the brain
- warm-blooded, controlled by the brain
- a placenta in the womb
Interestingly enough, bearing live young is not considered a trait of mammals, since there are several groups that are considered mammals that do not do this.
Many mammals don't have ALL these characteristics, but they all have MOST of them. And dolphins are no exception, of course! It almost goes without saying that dolphins have advanced brains... even for mammals. Dophins DO produce milk, and young nurse for up to two years.
About the only characteristic they don't SEEM to meet is the hair one. But though adult dolphins don't have hair, they are born with very fine hairs near their snout. Which is enough for most biologists.
Gross physical features aside, genetic evidence indicates that they are pretty closely related to land mammals, having diverged about 50 million years ago. It's always nice to get the biochemical confirmation!
Fish, on the other hand, are cold-blooded, have gills, and two sets of paired fins as well as other unpaired fins. Dolphins are not cold-blooded, they don't have gills, and most only have one set of (pectoral) fins. A total non-match!
2007-03-05 10:00:26 · answer #1 · answered by Doctor Why 7 · 1⤊ 0⤋
They share many chracteristics with other mammals. The most prominant two would be.
1. Give birth to live young
2. Female produce milk for the nourishment of young
2007-03-05 18:32:15 · answer #2 · answered by Yarra 3 · 0⤊ 0⤋
They suckle their young - which is a definition of a mammal.
They have no gills, fish do. Dolphins get their oxygen from air like other mammals
2007-03-05 18:01:22 · answer #3 · answered by rosie recipe 7 · 0⤊ 0⤋
Dolphins give live birth, Breath air and have small bristle like hairs on their bodies
2007-03-05 18:53:21 · answer #4 · answered by Micky D 3 · 0⤊ 0⤋
Critical differences are:
Fish have: Scales, gills (can breath in water)
Mammals have: hair/fur, lungs, mammary glands (hence their name)
Dophins are clearly mammals. They just hold their breath under water.
2007-03-05 17:49:55 · answer #5 · answered by J 5 · 0⤊ 0⤋
cause dolphins have birth like humans and fish lay eggs.
2007-03-05 18:00:16 · answer #6 · answered by mimigirl 1 · 0⤊ 0⤋
they breathe air give birth to live young produce milk and have no scales, some types have small amounts of hair
2007-03-05 17:48:12 · answer #7 · answered by The Thinker 2 · 0⤊ 0⤋
1st they give live birth to their young and 2nd they have lungs. They also have hair
2007-03-05 17:48:19 · answer #8 · answered by ID Guy 2 · 0⤊ 0⤋