phylum arthropod echinoderm pl - echinoderms. • sea stars, sea ... locomotion, and strong...
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Review Inverts What Invertebrates have we learned about so far?
Cnidaria jellyfishes, sea anemones, coral
Ctenophora comb jellies
Molluscs snails, bivalves, octopuses, squid, cuGlefish
Largest phylum on earth 1,000,000 + species and several million
Phylum Arthropoda characteristics: Segmented bodies Bilateral Symmetry Jointed legs Exoskeleton Tough, non-living
external skeleton Made of chitin Protection, support,
Molting Molting is when the exoskeleton is
shed as the organism outgrows it.
Majority of marine arthropods are crustaceans
Barnacles, shrimps, lobsters, crabs, and a variety of others
Crustacean Characteristics Two simple, compound eyes; two pairs of
antennae, three pairs of mouthparts. The abdominal segments have
swimmerets (swimming legs) Gills for respiration The sexes are separate. Eggs are
attached to the swimmerets of the female. Open circulatory system (there is no blood flow in a closed loop).
Primitive nervous system (similar to earthworm).
Superclass Crustacea: Characterized by two pairs of antennae, mandibles for chewing, a pair of appendages on each segment and teardrop shaped larvae.
Crustaceans include lobsters, crabs, shrimp, copepods, krill
The order Decapoda have ten functional legs and an extended carapace (shell) that covers the gills.
Crustaceans: Decapods (10 legs)
Largest group of crustaceans (10,000 species)
Includes shrimp, lobsters, crabs
Largest crustaceans in size 14 lb Alaskan King Crab
Filter feeders Usually attached to
surfaces (whales, crabs, rocks)
Bodies enclosed by heavy plates
Use cirri to sweep the water and feed
A dead spider crab hung up next to a man for comparison !
Use mouth parts to capture food
Large antennae used for sensory reception
More crustaceans Copepods and krill = major part of the
food web that supports the basis of life in many marine ecosystems
Echinoderms Phylum Echinodermata meaning Echinoderms have spiny skins. They have radial symmetry. They lack body segmentation. There are more than 5000 species
of Echinoderms. Sea stars, sea urchins, sea
cucumbers, sand dollars.
Sea Stars- Starfish Most starfish have 5
armsor rays. Starfish have tube feet for
locomotion, and strong suction to hold them in place.
They also have a water vascular system that enables them to store water and keep them rigid
They breathe through small gills in their skin.
Mouths are located on the underside of their bodies.
Starfish can regenerate. (must have the central disc attached).
Echinodermata Movement: tube feet of the water vascular system project out and suction to things
A Variety of Echinoderms Sea Stars - common starfish
Sea stars are predators. They feed on other invertebrates, e.g., gastropods, bivalves. Sea stars can attack and digest prey by everting their stomach. They can insert stomach through a small opening in a clams shell and digest the meat inside.
Brittle Stars Class Ophiuroidea: slender legs are
longer and thinner than sea stars. Basket stars are brittle stars with highly
developed arms that open like a net to catch plankton.
Sand Dollars and Sea Urchins: Class Echinoidea
Sea urchins help control algae growth on coral reefs by grazing on algae. Be careful of their spines!
Live just below the surface of sand or mud. Velvety spines usually gone when washed up on beach.
Sea Urchins Sea Urchins look
like big pin cushions.
They use these spines for protection against predators.
Herbivores that eat mostly algae.
Sea Urchin Anatomy
Sand Dollars Are found on the sandy shore or muddy
bottoms. They feed standing on edge with their
tube feet acting as filters. The star pattern seen on top of the sand
dollars is actually caused by special breathing tube feet!
The mouth is found on the under side of the animal.
Sand Dollar Anatomy
Sea Cucumbers Tentacles at their mouth openings to grab
and hold food. Look like snails, but have radial symmetry
and spiny bodies like all other echinoderms.
When provoked, or annoyed, sea cucumbers throw out their intestines to entangle, frighten, or confuse their predator! Then the intestines are regenerated.
Sea Cucumbers are considered a delicacy in Asian cultures.
Interesting Stuff Some Sea cucumbers are poisonous, and
the poison has been used as an inhibitor of Cancer growth.
Sea Cucumbers secrete a sticky glue as a defense mechanism that has been used as a bandage to bind wounds.
Sea Cucumbers will stick each tentacle in their mouths, lick them off and then do the same with the next one- kind of like you licking your fingers after eating!
Sea Cucumber Anatomy