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A Survey of Marine Animal Kingdoms

Mollusks --- A Bag, a Scraper, and a Foot •  Phylum Mollusca

characteristics –  Mantle: muscular bag

circulates water –  Foot: beneath the

head used for crawling by snails or propulsion by squid, octopuses

–  Radula: rough, scraping teeth (except bivalves)

Classes: gastropoda (snails, whelks), bivalvia (clams, scallops), cephalopoda (octopuses, squid, cuttlefish)

Gastropods "  They make up over 2/3 of all the Mollusk

species. "  Gastropod means “stomach foot”. "  Snails and Nudibranchs are the most

common Gastropods.

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Class Gastropoda

•  Many snails can withdraw into the shell and close it off with a horny operculum.

Gastropod Feeding Habits

•  Most gastropods are herbivores and feed by scraping off algae using the radula.

•  Some are scavengers of dead organisms

•  Others are carnivores that drill into other mollusks

SNAIL MOUTH

MOUTH WITH RADULA

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COLORFUL MOON SNAIL

NORTHERN ABALONE

CONE SNAILS

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HORSE CONCH •  Florida state shell •  Voracious carnivore

QUEEN CONCH

Ocular notch

Busycon

Naticidae

Gastropod egg cases

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SHELL-LESS GASTROPODS

SEA SLUGS & NUDIBRANCHS

NUDIBRANCH MEANS “NAKED GILL”

SHELL-LESS ANIMALS MUST PROTECT THEMSELVES WITH POISON/TOXIN,

KEPT IN CERATA OR MUCUS

BRIGHTLY COLORED TO “ADVERTISE” POISON

ELEGANT NUDIBRANCH

Florida Sea Goddess

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SPOTTED SEA HARE Parapodia

Bi-Valves

Class Bivalvia

•  Bivalve mollusks have two shells (valves) that are hinged.

•  clams, oysters, scallops, cockles, mussels, shipworms

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Bi-Valves "  Sessile. Filter feeders "  NO radula "  They take in, and release, water

through a Siphon. "  They breathe using Gill Membranes. "  Some Bi-Valves are motile, some are

Sessile. "  They have separate sexes with

sperm and eggs being released into the water (external fertilization).

Clam Anatomy

Soft-bottom burrowers •  Rely on blade-like foot for burrowing •  Rely upon long siphons

Cockle

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CEPHALOPODS HI KIDS, MY NAME IS SQUIDWARD.

WANNA MEET SOME OF MY RELATIVES?

Class Cephalopoda: head-foot •  Fast moving, aggressive predators that

capture prey with their tentacles, bite with parrot-like beak and shred the meat with their radula.

Octopuses Squid Cuttlefish

CHARACTERISTICS •  MOST ADVANCED OF THE MOLLUSKS

•  EYES ARE HIGHLY DEVELOPED

•  ACTIVE SWIMMERS – …

•  ARMS & TENTACLES HAVE SUCTION CUPS TO HOLD PREY

•  BEAK-LIKE MOUTH TO BITE PREY

•  VENOM IN SALIVA PARALYZES PREY

•  CAN CHANGE COLOR RAPIDLY

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Class Cephalopoda

•  Most cephalopods have complex eyes with cornea, lens, chambers, and retina.

•  Largest invertebrate brain

•  Closed circulation

Class Cephalopoda - Locomotion

•  Cephalopods swim by expelling water from the mantle cavity through a ventral funnel.

Protection •  Color changes effected by chromatophores

(pigment cells) •  Allows them to blend into their background •  Squirting out water by jet propulsion helps

escape predators •  Squids also release an inky substance into the

water

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Class Cephalopoda - Reproduction

•  Sexes are separate in cephalopods.

•  Juveniles hatch directly from eggs – no free-swimming larvae.

•  One arm of male removes a spermatophore from mantle cavity and inserts it into female.

SQUID

2 TENTACLES

8 ARMS

SIPHON

VERY ACTIVE SWIMMERS

COMMONLY FOUND IN SCHOOLS

VERY AGGRESSIVE PREDATORS

BEAK OF

SQUID

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SQUID SUCKERS

GIANT SQUID

GIANT SQUID

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SQUID EGGS

RMJA

OCTOPUS RARELY SWIMS, CRAWLS WITH 8 ARMS LIVES IN HOLES/CREVICES/BURROWS FEEDS AT NIGHT – NOCTURNAL PREDATOR SQUIRT INK AS A DEFENSE TO ESCAPE

VISCERAL MASS

8 ARMS

SIPHON

http://www.eumed.net/malakos/Imahispa/Argonauta%20nouryi.jpg

Octopus vulgaris

Octopus briareus

Octopus vulgaris

Sepioteuthis sepioidea

Octopus joubini

CEPHALOPODA

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GIANT PACIFIC OCTOPUS

CHAMBERED NAUTILUS