Scaphopoda
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By
Seymour Scaphopoda
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Hello, my name is Seymour Scaphopoda and I'm here to tell you about my Class, the Scaphoda. We are often known and called by our more common name, the "Tusk Shells".
I, as do all the members of my Class, live in the marine environment (salt-water habitat) only. We all live in a shell house that we build to protect our very soft body. There are about 350 different species in our Class living in shallow to relatively deep (2,000 meters) water. We range in size from 2 millimeters to about 15 centimeters (1/16th of an inch to 6 inches).
Some of our shells look like an elephant s tusk, while others look like a swollen cucumber. Whichever shape we take, our shells are open a both ends making us look like a fat drinking straw that has swallowed a big lunch. This tube-like shell usually has several heavy ribs running the length of it and it is most often coloured white and brown or white and green.
We tusk shells have a spade-shaped (like a shovel) foot that we use to dig ourselves into the soft muddy or sandy ocean bottom. Here we stay all our lives.
We draw water in through the small tip of our shell that sticks out of the sand or mud where we live. This water flows into our mantle cavity (remember, the mantle is the organ that builds our shells) where oxygen is just absorbed directly into our blood. We do not have gills for breathing, nor do we have a heart or blood vessels to carry and pump our blood. We are what scientists call "a very primitive and simple organism".
My cousins and I always live head down in the sand or mud. We have many skinny thread-like tentacles that have a tiny sticky pad at their tip. These captacula project from our heads and wiggle through the surrounding mud or sand in search of food. These fine threads, called captacula, latch onto very small food items (called detritus) found in the sand or mud and then they pull them in to our mouth. From there, the food is rasped by the radula (which looks and acts much like a fingernail file) into finer particles and is then digested.
Both the females and males of my Class release their eggs and sperm directly into the surrounding water. If, by chance, the eggs and sperm get together, fertilization occurs and a baby scaphoda is born.
Some
interesting Scaphopoda facts:
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