File

4/20/2016
A Survey of Marine Animal
Kingdoms
Advanced Invertebrates Have Complex
Bodies and Internal Systems
Mollusks
• (Bi-Valves, Gastropods, and
Cephalopods)
Mollusks --- A Bag, a Scraper, and a Foot
• Phylum Mollusca
• Bilateral symmetry
• Well developed nervous
systems
• One-way digestion
• Three main parts
– Mantle: muscular bag
circulates water; houses
the gills, stomach and
heart
– Muscular Foot: beneath
the head used for crawling
by snails or propulsion by
squid, octopuses
– Radula: rough, scraping
teeth (except bivalves)
Head-Foot Region
• The radula is a
rasping, tongue
like feeding
structure found in
most mollusks
except bivalves.
• Has tiny rows of
teeth for
scraping.
Head-Foot Region
• Most mollusks have well developed head
ends with sensory structures that may be
simple light detectors or complex eyes
(cephalopods).
Shells
• Found in snails, bivalve mollusks,
chitons, and nautilus
• Made of calcium carbonate (limestone)
• Secreted by the mantle
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Internal Structure & Function
• Many mollusks have an open
circulatory system with a pumping
heart, blood vessels and blood
sinuses.
• Most cephalopods (squid &
octopus) have a closed circulatory
system with a heart, blood
vessels and capillaries.
Major Mollusk Classes
• Four major classes of
mollusks:
– Class Polyplacophora –
the chitons
– Class Gastropoda –
snails & slugs
– Class Bivalvia – clams,
mussels, oysters
– Class Cephalopoda –
octopus & squid
Gastropods
They make up over 2/3 of all the Mollusk
species.
Gastropod means “stomach foot”.
Snails and Nudibranchs are the most
common Gastropods.
Mollusk Life Cycle
• Most mollusks are
dioecious (separate
sexes)
• Some are
hermaphroditic
• The life cycle of
many mollusks
includes a free
swimming, ciliated
larval stage called a
TROCHOPHORE
Class Polyplacophora
• Includes the chitons
• Eight overlapping
plates
• Can roll up
• Live mostly in the
rocky intertidal
zones.
• Use radula to scrape
algae off rocks.
• Water flows over
gills to respire
Class Gastropoda
• Many snails
can withdraw
into the shell
and close it
off with a
horny
operculum.
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Gastropod Feeding Habits
Gastropod Anatomy
• 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
LOCOMOTION Diversity
Burrowing
foot enlarged & plow-like.
(moon & olive snails).
Swimming
Foot Expanded as swimming fin(s).
(heteropods, “pteropods”)
Floating
Purple sea snails (Janthinidae)
secrete raft of mucus bubbles.
Sessility - Few attached to rocks as adults.
(Vermetidae – worm snails,
Calyptraeidae –slipper snails)
NORTHERN ABALONE
COLORFUL MOON SNAIL
CONE SNAILS
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HORSE CONCH
QUEEN CONCH
• Florida state shell
• Voracious carnivore
Ocular
notch
Busycon
SHELL-LESS GASTROPODS
Gastropod egg
cases
SEA SLUGS & NUDIBRANCHS
NUDIBRANCH MEANS “NAKED GILL”
Naticidae
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
Bi-Valves
Parapodia
Class Bivalvia
• Bivalve mollusks
have two shells
(valves) that are
hinged.
• clams, oysters,
scallops, cockles,
mussels, shipworms
Clam Anatomy
Bi-Valves
Sessile. Filter feeders
NO radula
They take in, and release, water
through a Siphon Tube.
They breathe underwater using Gill
Membranes.
Some Bi-Valves are swimmers, such
as scallops.
They have separate sexes with
sperm and eggs being released into
the water (external fertilization).
Soft-bottom burrowers
• Rely on blade-like foot
for burrowing
• Rely upon long siphons
Cockle
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Cemented surface dwellers: No bysuss
Surface dwellers attached via
byssus: threadlike anchors
Several unrelated groups of “oysters” independently evolved ability to
cement on one side.
True oysters (Ostreidae), jewel boxes (Chamidae), thorny oysters
(Spondylidae).
Pen Shell
Arcidae
Oyster
Oyster
Pinnidae
Oyster reef
Oysters
Winged
oysters
Tridacnidae
Giant Clam
Mussels
Jewel box
Pteriidae
CEPHALOPODS
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NAME IS
SQUIDWARD.
WANNA MEET
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RELATIVES?
Class Cephalopoda
• Most cephalopods
have complex eyes
with cornea, lens,
chambers, and
retina.
• Largest
invertebrate brain
• Closed circulation
Thorny oyster
CHARACTERISTICS
• MOST ADVANCED OF THE MOLLUSKS
• ACTIVE SWIMMERS – …
• EYES ARE HIGHLY DEVELOPED
• ARMS & TENTACLES HAVE SUCTION
CUPS TO HOLD PREY
• BEAK-LIKE MOUTH TO BITE PREY
• VENOM IN SALIVA PARALYZES PREY
• CAN CHANGE COLOR RAPIDLY
Class Cephalopoda - Locomotion
• Cephalopods
swim by expelling
water from the
mantle cavity
through a
ventral funnel.
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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
SQUID
VERY ACTIVE SWIMMERS
COMMONLY FOUND IN SCHOOLS
VERY AGGRESSIVE PREDATORS
8 ARMS
2 TENTACLES
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.
BEAK
OF
SQUID
SIPHON
SQUID SUCKERS
GIANT SQUID
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SQUID EGGS
GIANT
SQUID
RMJA
CEPHALOPODA
Octopus joubini
OCTOPUS
RARELY SWIMS, CRAWLS WITH 8 ARMS
LIVES IN HOLES/CREVICES/BURROWS
FEEDS AT NIGHT – NOCTURNAL PREDATOR
SQUIRT INK AS A DEFENSE TO ESCAPE
Caribbean
reef octopus
Atlantic pygmy
octopus
Octopus briareus
http://www.eumed.net/malakos/Imahispa/Argonauta%20nouryi.jpg
Octopus vulgaris
VISCERAL
MASS
Octopus vulgaris
Caribbean reef Sepioteuthis
sepioidea
squid
8 ARMS
SIPHON
GIANT PACIFIC OCTOPUS
Common octopus
CHAMBERED NAUTILUS
Trapped gas
bubbles keep
the nautilus
buoyant
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