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invertebrate

Sea Stars

One of the most recognizable marine species, sea stars typically have a five-part body consisting of a central disk and radial symmetry. Size, shape, color and texture are quite diverse in the 1,800 species that inhabit our oceans worldwide, today. Like its close relatives in the Echinoderm phylum like sea urchins and sea cucumbers, sea stars share many of the same characteristics. Mouth is located on the underside and use tube feet as a mode of locomotion.

Sea stars are predators and scavengers. A diverse diet include other echinoderms, including spiny sea urchins, a sea stars everts its stomach over their prey and digest their food outside of their body or swallow it whole. Others prey on sessile animals like sponges, anemones or coral polyps using the same method of everting its stomach. A few other species eat detritus material, algae and clams and oyster shells.

Sea stars, like most echinoderms, reproduce by simultaneously release eggs and sperm into the water column. Once fertilized, eggs hatch into free-swimming larvae that eventually settle at the bottom. Another means of reproducing is by detaching an arm (autotomy) or splitting apart (fission) where a completely new animal forms.

Hawai‘i has 20 known shallow water species and 68 deep sea species. Even then, sea stars are not commonly seen in tide pools or shallow waters by beachgoers, those with a keen eye might spot an arm peering out of a small crevice.

*Due to the constant rotation of animals back to the ocean, the presence of any specific animal cannot be guaranteed.

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