What type of skeleton do starfish possess?

Starfish, or sea stars, possess a hydrostatic skeleton, which is a type of support system that relies on the pressure of internal fluids. In starfish, the body is supported by a fleshy, water-filled coelom (the body cavity). This hydrostatic environment allows for movement and structural support, giving the starfish its unique ability to navigate its surroundings and extend or retract its arms.

The hydrostatic skeleton works by using water pressure to help maintain the rigidity and shape of the organism. When muscles contract, they create a change in pressure within the fluid, affecting how the limbs move. This is particularly important for starfish, as they rely on this system to operate their tube feet, which they use for locomotion and feeding.

In contrast, an endoskeleton is an internal support structure found in vertebrates and some invertebrates, while an exoskeleton refers to an external hard structure, typical of arthropods like insects and crustaceans. A cartilaginous skeleton, primarily made of cartilage rather than bone, is characteristic of certain fish like sharks and rays. Each of these options highlights different types of biological structures, with the hydrostatic skeleton being the correct choice for starfish due to their unique physiological traits