Monday, 30 May 2016

Key's Marine Lab: Cushion Star Fish

A week in the Key’s was just as much fun as it sounds! From the moment we were awake on the first day we were boarding a boat to go snorkeling. The first thing I noticed was the abundance of fish because they were the most obvious, then as the coral was pointed out I began to notice the different species of coral. But what I enjoyed finding the most were the cryptic invertebrates inhabiting the sandy bottom. Each of these strange creatures living in the shallows was enticing, though the one that caught my attention the most was a rather large sea star with a thick center and arms all topped with dull projections. At the time that I saw this beautiful star all but glistening on the shallow sea floor I had very little knowledge of sea stars. When I got back from the boat trip I used one of the field guides coupled with the vast knowledge of Dr. Voss and identified this majestic creature as the cushion sea star, also called the Bahama sea star (Oreaster reticulatus). The cushion sea star is a member of the phylum Echinodermata. This is the same phylum as sea urchins, sand dollars and sea cucumbers. Animals in this phylum have radial symmetry which means that unlike animals with lateral symmetry (like humans) they have multiple points of symmetry. Sea stars also use a water vascular system coupled with their tube feet for locomotion. they force water into the tubes on the bottom of their arms and with the hundreds of feet working together they are able to move across the bottom. The cushion sea star in particular is found most commonly on sandy bottoms and amidst coral ruble. When it comes to feeding the cushion sea star does not seem very picky. They are omnivores and will extrude their stomachs onto sea grasses and algal substrates and digest it externally. They will also feed on slow moving or sessile animals, on occasion they will even feed on other star fish. The cushion star was cool to learn about and the whole experience in the Key’s was great, I’m excited to see what is next in this adventure!

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