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Review  Inverts  •  What  Invertebrates  have  we  learned  about  so  far?  

•  Porifera    – sponges  

•  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

undiscovered

•  Phylum Arthropoda characteristics: – Segmented bodies – Bilateral Symmetry – Jointed legs – Exoskeleton §  Tough, non-living

external skeleton § Made of chitin §  Protection, support,

flexibility

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Molting •  Molting is when the exoskeleton is

shed as the organism outgrows it.

Marine Arthropods

•  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).

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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

Crustacean diversity

Shore crabs

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Crustacean diversity

Bashful crab

Arrow crab

Swimming crabs

Lobster

Crustaceans: Barnacles

•  Filter feeders •  Usually attached to

surfaces (whales, crabs, rocks)

•  Bodies enclosed by heavy plates

•  Use cirri to sweep the water and feed

http://www.vincelewis.net/spider.html

A dead spider crab hung up next to a man for comparison !

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Crustaceans: Copepods

•  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.

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Sea Stars- Starfish •  Most starfish have 5

“arms”or 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 clam’s shell and digest the meat inside.

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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.

•  Keystone species

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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.

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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.

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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