Sea Cucumbers.
Hardened plates of calcium carbonate form its endoskeleton.
Endoskeleton
Echinoderms have an Endoskeleton made up of 95 % calcium carbonate.
Echinoderms, such as sea stars and sea urchins, have an endoskeleton made of hard plates called ossicles that lie inside their bodies. Although this endoskeleton is internal, it functions similarly to an exoskeleton by providing support and protection. It allows echinoderms to control their body shape and movement, just like an exoskeleton does for other invertebrates.
There are many. The only phylum that contains invertebrates with exoskeletons are Echinoderms. An example is cuttlefish.
Echinoderms possess a unique endoskeleton composed primarily of calcareous plates or ossicles, which are embedded within their mesodermal tissue. This endoskeleton provides structural support and protection while allowing for flexibility and movement, particularly through the use of tube feet. The ossicles can vary in size and shape, contributing to the diverse forms of echinoderms such as sea stars, sea urchins, and sea cucumbers. Additionally, the endoskeleton plays a role in locomotion and defense against predators.
The first organisms to develop a hardened endoskeleton were likely ancient invertebrates called echinoderms, such as sea urchins and starfish. Their endoskeleton is made of plates composed primarily of calcium carbonate. This adaptation provided structural support and protection as these organisms evolved to live in various marine environments.
Sea Stars otherwise known as Star Fish are Echinoderms and they do not have an exoskeleton, they have an endoskeleton.
Closed hydrovascular for echinoderms, open haemolymphatic for arthropods. ^^
No, echinoderms do not have backbones. They are a group of marine animals that includes starfish, sea urchins, and sea cucumbers, and they belong to the phylum Echinodermata. Instead of a backbone, echinoderms have a hard, calcareous endoskeleton made up of ossicles, which are small calcium carbonate structures. This unique skeletal system provides support and protection without the presence of a vertebral column.
Humans and crocodiles have endoskeletons
A cheetah has an endoskeleton, which is an internal skeleton.