Transcript The Common Sand Dollar Powerpoint

Echinarachnius parma
By Katie Wallace
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Kingdom: Animalia
Phylum: Echinodermata
Class:Echinoidea
Order: Clypeasteroida
Family: Echinarachniidae
Genus: Echinarachnius
Species: parma
Habitat
• The common sand dollar can be found on the
east coast of North America, Siberia and
Japan.
• They live in the sand in intertidal zones.
• They have a “test” that covers the entire sand dollar. The “test”
is entirely made up of calcium carbonate.
• They are flat on the bottom and have a slight round curve on the
top. They have radial symmetry.
• On the top you can find an outline that is in the shape of a
flower (specifically a poinsettia), there are “podia” located here.
• There are tiny grooves on the bottom part of the sand dollar
which have “black spines” that trap food.
• “Cilia” near the mouth help to guide food, and prevent the sand
dollar from being washed away by currents by burrowing in the
sand.
• Sand dollars may or may not have oval-shaped slits that go
through the entire body.
• The mouth can be found in the very center of the bottom side of
the sand dollar.
• Over time, sea urchins evolved into sand dollars, and
went from being shaped like a ball, to flat and round.
• This adaptation was for burrowing purposes.
Sand dollars have what is called a “test”. It surrounds the
sand dollar entirely and protects it from the elements. It
is made up of very tiny spines and it may also be known
as a shell.
There are tiny spikes that stick out on either side of the
mouth. They prevent the sand dollar from being swept
away by the current in the ocean, and they help it
burrow in the sand.
Respiration and movement, and circulation all use
the same system, called a “water vascular system”,
to function. Sea water is pumped into their “tubelike” feet, which are connected to canals that travel
throughout the sand dollar. These canals allow the
sea water to travel through the body.
• Sand dollars don’t have gills!
• In respiration, the oxygen from the
sea water in the canals is absorbed
through the walls, rather than
through gills.
• This process is called diffusion.
• Sand dollars move by contracting muscles in
opposite directions
• This forces the sea water from the canals into
the tube feet and back into the ocean,
causing the sand dollar to lift off the sea
floor.
They get into their vertical position for feeding by forcing the water out of one side of the
sand dollar, causing half of it to lift, while the other half stays on the seafloor. Once it is
completely vertical, it waits for food to come its way.
• Sand dollars have a very simple circulatory
system.
• it is also controlled by the “water vascular
system”, this means that its powered by
the movement of water through the
canals.
• Contracting muscles cause the water to
continuously move throughout these
canals
• Sand dollars reproduce like sea urchins.
• Depending on whether a sand dollar is female or male, it
releases its sperm/eggs into the water.
• Not too long after the eggs are fertilized, they become
larvae, and float freely in the ocean until they begin the
next stage of their life. Larvae are mobile, which means
they don’t move themselves, they allow something else to
move them.
• The larvae still has a long way to go before it becomes a
fully grown sand dollar. There are still many more stages of
the lifecycle before the adult stage.