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PHYLUM MOLLUSCA. PHYLUM MOLLUSCA. Invertebrates Freshwater, marine, & terrestrial Largest marine phylum 23 % of named marine species Mantle Radula Ventral foot. CLASS CEPHALOPODA. Squids, octopods, cuttlefish, Nautiloidea Bilateral symmetry Marine Arms or tentacles.
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PHYLUM MOLLUSCA • Invertebrates • Freshwater, marine, & terrestrial • Largest marine phylum • 23% of named marine species • Mantle • Radula • Ventral foot
CLASS CEPHALOPODA • Squids, octopods, cuttlefish, Nautiloidea • Bilateral symmetry • Marine • Arms or tentacles
ORDER TEUTHIDA – SQUIDS • 8 arms in pairs of 2 • 2 tentacles (usually longer) • Largest eye-to-body ratio
FAMILY LOLIGINIDAE • “pencil squids” • Body tapers to a point • Arms are partially retractable • Buccal membrane has 7 lappets
Sepioteuthissepioidea • Caribbean reef squid • Cigar-shaped body • Arms shorter than body • 10-20 cm long • Fins extend almost whole length of body • Undulate rapidly as they swim
Sepioteuthissepioidea • Unique behaviors • Pointing bodies upward prior to striking prey • Curling upward during territorial disputes • Pointing head-down when approached by predators • Found in Caribbean sea and off the coast of Florida • Young congregate in turtle grasses • Die after reproducing (like other cephalopods) • First squid to be observed “flying”?
ORDER OCTOPODA • 8 arms • No shell
FAMILY OCTOPODIDAE • Majority of know octopods • Bottom-dwelling • Suckers in one or two series • One arm modified as open sperm groove in males
Octopus briareus • Caribbean reef octopus • “Chunky” body compared to arms • 40 – 60 cm long, up to 1.5 kg • Dark ring around eye • No dark borders on suckers
Octopus briareus • Cannibalistic when confined in small tanks with others • Nocturnal hunters • Reflective skin is easy to see at night • Uses chromatophores for camouflage • Disguise themselves as other species or objects • One of the most intelligent invertebrates • Very little sexual dimorphism • Also die after reproducing • Females live long enough to guard eggs