The phylum Echinodermata , which contains about 6000 species, gets its name from the Greek, literally meaning "spiny skin." Many echinoderms actually do have "spiny" skin, but others do not. This phylum exists exclusively in the sea, and cannot be found on land or in fresh water. All echinoderms have one thing in common: radial symmetry. This means that the creatures have appendages (or body construction) which point outward from the center of the body like the spokes on a bicycle wheel. Furthermore, these appendages usually occur in multiples of five, although there are a few exceptions. There are several well known members of this group, like sea stars and sea urchins. The radial symmetry is obvious in these creatures.
The structures that are responsible for producing semen are within the make reproductive system. these include the testes, epidymus, prostate, seminal vesicles, and the bulbourethral gland.
It probably needs to dig in the ground for worms and grub. So it's an adaptation for finding food.
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The mitochondrion is a membrane-bound organelle that provides energy by ATP synthesis (oxidative phosphorylation)
The lysosome contains about 40 hydrolytic enzymes that help with cellular digestion.
The Golgi apparatus plays an important role in the excretion and packaging of vesicles.
