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
Sepioteuthis sepioidea
 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
Sepioteuthis sepioidea
 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”?
Squid Flight
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