Are dolphins considered mammals, and what determines if an animal is a mammal or not?

Answer 1

Yes, dolphins are mammals; specifically, they belong to order Cetacea.
Neither warm-bloodedness nor air-breathing are characteristics that define mammals, since they're shared with other animal groups.
Basically, a mammal has 4 major traits:
1) Hair
2) Mammary glands that produce milk to feed the young
3) Lower jaw formed by a single bone, the dentary, and
4) Middle ear with three ossicles: hammer, anvil and stirrup

Only mammals have these four diagnostic characteristics. Many people confuse them, and mention other traits that are not diagnostic.
Examples:
-- live-bearing: the platypus and the echidnas are mammals and lay eggs
-- warm-blooded: so are birds, as well as some fish and marine turtles
-- air-breathing: all terrestrial vertebrates have lungs.

Hair is very reduced in dolphins, but they possess hairs when they're embryos, and they retain hair-associated structures after they're born, especially as sensitive areas on their head.

Answer 2

What Determines A Mammal

Answer 3

Dolphins are mammals.
There are 5 things to classify mammals they need to have all of them to be considered a mammal.
1.) Live Birth
2.) Feed baby Milk
3.) Warm Blooded
4.) Hair
5.) Breath air

Answer 4

Mammary glands = Mammals

Any animal that has mammary glands and feeds its young with milk from them is a mammal.
Mammals also carry young inside our bodies in a sac called placenta.


Dolphin females have mammary glands on each side of the vagina.
The glands are internal and the young has to use its snout to burrow deep enough to suckle.
Feeding lasts from 3 to 30 seconds on average, and although this seems short, the milk is extremely rich so the length of suckling does not matter.

Answer 5

Dolphins are mammals and belong to the same order that whales do, which is the order Cetacea. Just like humans, dolphins breathe air and cannot stay under water for too long or they will die.
All mammals also give live birth, & suckle their young.

Answer 6

Yes, dolphins are considered mammals. All mammals have body hair (whether it's a lot or a little). Also, all female mammals have mammary glands, thus allowing them to feed their offspring.

So, basically, If an animal drinks milk when it is a baby and has hair on its body, it belongs to the mammal class.

Answer 7

Dolphins are amoung the group of marine mammals refer to as Cetaceans; whales, porpoise and dolphins.
http://www.acsonline.org/education/taxonomy.html

Yes, dolphins are mammals. Characteristics dolphins share with other mammals are, warm blooded, breathe air, and nurse young on milk from mammary glands.

Dolphin (aquatic mammal)
http://encarta.msn.com/encyclopedia_761552786/Dolphin_(aquatic_mammal).html

Mammalian Characteristics
http://www.lcsc.edu/mjbrady/mammalogy%20lectures/mammalian_characteristics.htm

Answer 8

Dolphins ARE mammals. Mammals are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex region in the brain. Most mammals also possess specialized teeth and utilize a placenta in the ontogeny. The mammalian brain regulates endothermic and circulatory systems, including a four-chambered heart.

Answer 9

Warm-blooded vertebrate animals of the class Mammalia that are characterized by a covering of hair on the skin and, in the female, milk-producing mammary glands for nourishing the young.

Dolphins don't have hair so are classed as marine mammals, which are primarily ocean-dwelling or depend on the ocean for their food. Interestingly, mammals originally evolved on land, but later marine mammals evolved to live back in the ocean.

Answer 10

Dolphins are mammals. A mammal is a warm-blooded animal that nourishes their young with milk secreted by the mammary glands.