starfish


Starfish are also referred to as sea stars because of their star-shaped appearance. They are a part of the phylum Echinodermata and are related to sand dollars, sea urchins, and sea cucumbers. Echinoderms are found in nearly all marine habitats and constitute a major proportion of the biomass. Starfish belong to the class Asteroidea, derived from the Greek words “aster” (a star) and “eidos“ (form, likeness, appearance). There are more than 1600 species of starfish alive today, and they have an important role in the community structure of the ocean floor.  



 

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Sharks

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Sharks use their gills to filter oxygen from the water. They are a special type of fish known as "elasmobranchs", which translates into fish made of cartilaginous tissues—the clear gristly stuff that your ears and nose tip are made of. This category also includes rays, sawfish, and skates. Their cartilaginous skeletons are much lighter than true bone and their large livers are full of low-density oils, both helping them to be buoyant.  Even though sharks don't have bones, they still can fossilize. As most sharks age, they deposit calcium salts in their skeletal cartilage to strengthen it. The dried jaws of a shark appear and feel heavy and solid; much like bone. These same minerals allow most shark skeletal systems to fossilize quite nicely. The teeth have enamel so they show up in the fossil record too.  How  to act if you see a shark
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