why are dolphins vertebrates?

Answer 1

All vertebrates have backbones. Types of vertebrates include fish, amphibians, reptiles, birds, and mammals. Dolphins are a type of marine mammal.

Dolphins, along with whales and porpoises, are thought to be descendants of terrestrial mammals, most likely of the Artiodactyl order. Dolphins entered the water roughly fifty million years ago. Dolphins have a streamlined fusiform body, adapted for fast swimming. The basic coloration patterns are shades of gray with a light underside and a distinct dark cape on the back. It is often combined with lines and patches of different hue and contrast.

Modern dolphin skeletons have two small, rod-shaped pelvic bones thought to be vestigial hind legs. In October of 2006, an unusual Bottlenose Dolphin was captured in Japan that had small fins on either side of the genital slit, which scientists believe to be a more pronounced development of these vestigal hind legs.

The head contains the melon, a round organ used for echolocation. In many species, the jaws are elongated, forming a distinct beak; for some species like the Bottlenose, there is a curved mouth that looks like a fixed smile. Teeth can be very numerous (up to two hundred and fifty) in several species.

The dolphin brain is large and has a highly structured cortex, which often is referred to in discussions about their advanced intelligence. A recent theory however disputes the existence of a neural basis for dolphin intellect, suggesting instead that the large brain is only an adaptation to living in cold water.

Unlike most mammals, dolphins do not have hair, but they are born with a few hairs around the tip of their rostrum which they lose after some time, in some cases even before they are born. River dolphins usually have them all their life and are believed to have a sensory function. Even in those species that lose the hair the hair follicles remain, and it is possible the nerves connected to them are still able to detect movements in the water.

Answer 2

Because a vertebrate has a spine and any animal with a spine is a vertebrate.

Answer 3

For the same reason that most fish are vertebrates -- they have vertebra.

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ver·te·bra
[–noun] any of the bones or segments composing the spinal column, consisting typically of a cylindrical body and an arch with various processes, and forming a foramen, or opening, through which the spinal cord passes.

Answer 4

Because, like all mammals, they have an internal skeleton.

Answer 5

Because, they have a spine.