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Class Cephalopoda the squids, octopus, nautilus, and cuttlefish
Richard E. Young, Michael Vecchione and Katharina M. Mangold Class Cephalopoda the squids, octopus, nautilus, and cuttlefish
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Class Cephalopoda shell is present, reduced, or lost
all are predacious with beak-like jaws highly developed head and sensory organs (very intelligent) closed circulatory system swim via jet propulsion foot is lobed and forms tentacles direct development (no larvae)
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Class Cephalopoda Reproduction
male transfers a spermatophore to female using a special pair of tentacles female seals herself up in a den to lay eggs which she attaches to the top of the den she cares for these eggs (in some species up to 6.5months) after the eggs hatch she usually dies
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Class Cephalopoda Nautilus:
have a chambered shell that aids in maintaining buoyancy chambers are filled with gas chambers siphuncle (cord of tissue connected to visceral mass)
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Ammonoids
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Class Cephalopoda Squids:
have a reduced, internal shell called the pen Cuttlefish: have a reduced, internal shell called a cuttlefish bone
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Spirula sp.
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Reduced Internal Shell
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Cephalopods have elaborate mating displays including complex courtship displays.
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Bioluminescence
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Class Cephalopoda Architeuthis sp. the largest giant squid found to date have been 18 meters in length they live in the deep sea sperm whales (~20m in length) are their major predators
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Robust clubhook squid Moroteuthis robusta (Cephalopoda: Onychoteuthidae) in Puget Sound (Washington State, USA)
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Robust clubhook squid Moroteuthis robusta
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Jumbo Flying Squid Dosidicus gigas
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Calamary
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Class Cephalopoda Octopus: have lost the shell completely
most intelligent invertebrate
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Giant Pacific Octopus Octopus dofleini
This species is one of the largest known octopods; the heaviest on record weighed nearly 600 pounds. It is fished commercially from Alaska to northern California. The Giant Pacific Octopus feeds on shrimps, crabs, scallops, abalones, clams, various fishes, and smaller octopods. It in turn is eaten by seals, sea otters, sharks, and other large predators.
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Giant Pacific Octopus Octopus dofleini
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Deadly venom and warning coloration
The Blue-ring Octopus Hapalochlaena maculosa It kills prey by delivering a poison in the saliva. The poison is a neurotoxin (maculotoxin) that is strong enough to kill a human being.
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The recently discovered mimic octopus (Octopus horridus) is, according to some sources, the coral reef’s great pretender. Some people have filmed, photographed and observed this octopus mimicing a great range of species including flatfish, seasnakes, jawfish, mantis shrimps, lionfish and others.
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Argonauta nodosa The paper nautilus
The paper nautiluses, Argonauta sp., are not nautiluses at all, they are octopuses! The paper thin white calcareous 'shell' is actually an egg case made by females.
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Argonauta nodosa The paper nautilus
Argoanuts are open-ocean cephalopods. In addition to small crustaceans, they ingest jellyfish!
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Argonauta nodosa The paper nautilus
The most sexually dimorphic cephalopods. The females are considerably bigger the males. Females are thought to live longer and reproduce many times while the tiny males are thought to only reproduce once and have much shorter life spans. During mating, one of the male's arms breaks off inside the mantle of the female. So both size and life span are radically different between the sexes.
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Class Polyplacophora the “Chitons”
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Class Polyplacophora have 8 rows of articulating plates
use radula to graze algae on substrate mantle forms a girdle around plate edge no veliger larvae girdle plates
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Cryptochiton sp. The Gumboot Chiton The gumboot chiton is one species of chiton that is a little different from the rest; it is the largest species of chiton in the world, growing up to 30 cm in length - and its eight plates are covered up by thick, leathery, brick-red flesh.
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Cryptochiton sp.
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Class Monoplacophora In 1952 ten living specimens of Neopilina were dredged from the deep ocean trench off the Pacific cost of Costa Rica. 3 mm-3 cm in size. Repetition of parts.
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Class Aplacophora
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Class Aplacophora Strange small worm like molluscs. Less than 5 mm.
Head is poorly developed and shell is absent. Cuticle contains calcareous scales or spicules.
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Class Scaphopoda the “tusk shells”
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Class Scaphopoda shell is modified into hollow tube that is open at both ends the mantle wraps completely around the visceral mass sessile and feed in sediment during reproduction produce trochophore larvae located above sand located below sand feeding tentacles
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Class Bivalvia (class Pelecypoda) the “bivalves”
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Class Bivalvia clams, mussels, oysters, scallops
use gills for respiration and filter feeding shell is modified into a bivalved shell connected by muscles and ligaments no head (reduced sensory organs), no radula foot can be modified for digging dorsal umbo -the oldest part of the shell anterior posterior ridges show where mantle has laid down shell ventral
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Introduction to Bivalves
Mollusks in the class Bivalvia originated in, and many have remained in the world oceans. Some have succeeded in colonizing fresh water habitats, and have radiated in species diversity. Bivalves as adults are an important part of the benthic infauna with restricted movement on and through the substrate.
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Bivalve Anatomy
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Cilia are used for filter feeding
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A LARGE UNIONID FILTER FEEDING
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Scolenidae and Cultellidae: Razor Shells and Jackknife Clams
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The Geoduck Panopea generosa a giant Californian bivalve, the body and siphon of which cannot be enclosed within valves
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Boring Bivalves (Shipworms: Teredinidae)
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Boring Bivalves
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Boring Bivalves
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Boring Bivalves
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Boring Bivalves
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Attached surface dwellers (Epifauna) Pen Shell Atrina rigida
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Pen Shell Atrina rigida
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They utilize byssal threads which are believed to represent a persistent larval adaptation
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Mussels (Mytilus sp.) Bassal threads
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The Giant Clam Tridacna sp.
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The Giant Clam Tridacna sp.
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