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Transcript 
Creeping
Varied diets
Living “fossils”
Reign of
Ammonites
Jet-propelled
Armed predators
Burrowing
Filter feeders
Benthic creepers
Algae feeders
Aplacophora
Worm-like burrowers
Detritus feeders
(Modified from Hickman & Roberts, 1995)
Subclass - Prosobranchia
Basal group
Subclass Opisthobranchia
Sea butterfly
Sea slug - nudibranch
Anal gill
Sea slug
Sea hare (Aplysia)
Opisthobranchia
90 degrees of detorsion
Often loss of shell, mantle cavity, gills
Some have extensions of mantle called
cerata with nematocyts.
Hermaphroditic
cerata
Opisthobranchia:
Nudibranch structure
Cerata
Pulmonata
Mantle cavity forms lung
Nitrogen excreted in uric acid
Eyes at the end of tentacles
escargot
Modern Pulmonate Gastropods
Garden Snail
Banana Slug
Escargot?
Creeping
Varied diets
Living “fossils”
Reign of
Ammonites
Jet-propelled
Armed predators
Burrowing
Filter feeders
Benthic creepers
Algae feeders
Aplacophora
Worm-like burrowers
Detritus feeders
(Modified from Hickman & Roberts, 1995)
Figure 33.22 Cephalopods: Squid (top left and bottom left), nautilus (top right),
octopus (bottom right)
Torsion
Visceral mass is dorsal
Gastropods vs. Cephalopods
Structure & Function
Coiled Shell
Distinct Head
Pulmonate Snail (gastropod)
Siphuncle
Septate shell
Arm-like tentacles
Closed circulatory system
Jet-propulsion
Nautilus (cephalopod)
Squid: Cephalopods without a shell
Pen = remnants of shell
Beaked jaws
Squid mantle anatomy
Cephalopods: Highly derived, complex nervous & sensory systems
To mantle
Cephalopod brain
Most complex of invertebrates
Huge optic lobes
To arms (muscular hydrostats)
“Giant axons”
High speed
conduction
Cephalopod Eye : Convergent on Vertebrates
Creeping
Varied diets
Living “fossils”
Reign of
Ammonites
Jet-propelled
Armed predators
Burrowing
Filter feeders
Benthic creepers
Algae feeders
Aplacophora
Worm-like burrowers
Detritus feeders
(Modified from Hickman & Roberts, 1995)
Bivalves - Pelecypoda
siphons
foot
Morphology of a Bivalve
Spatulate foot
No head
Expanded mantle
No radula
Filter feeding
(from Hickman & Roberts, 1995)
Circulatory, Respiratory &
Feeding Structures
(from Hickman & Roberts, 1995)
Bivalve locomotion
Form & function
Burrowing
Spade-like foot
Sessile (intertidal zone)
Anchored by Byssal Threads
Siphons (mantle)
Figure 33.20 A bivalve: Scallop
Giant Clam with Photobionts
Siphuncle
Beak-like jaws
Arm-like tentacles & siphon
Septate shell
Closed circulatory system
Byssus
Loss of radula
Bivalve shell
Torsion
Viscera concentrated dorsally
BENTHIC CRAWLER
ALGAE FEEDER
Tusk-shaped, open ended shell
Loss of gills
BURROWING SPECIALIZATIONS
FILTER FEEDING
Nervous system decentralized
Spatulate foot
Head reduced
Mantle expanded to surround body
Coiled shell
Distinct head
Shell of 7-8 plates
Mantle cavity extended alongside foot
Multiple gills
SCAPHOPODA
BIVALVARIA
JET PROPULSION
ARMED PREDATORS
CEPHALOPODA
GASTROPODA
POLYPLACOPHORA
Phylogeny of the Mollusca*
Single, well-defined shell gland
Shell is three layered
Shell univalve
Preoral tentacles
Chambered heart
Posterior mantles cavity with 2 gills
Radula
Muscular foot
Mantle producing a calcareous shell(s)
Reduced coelom
* Several minor classes excluded
Figure 32.8
Animal phylogeny
based on sequencing
of 18S-rRNA
Arthropods
Characteristic Features of Arthropod Body Plan
Body segmented (externally & internally)
Tagmosis & regional specialization of body
Locomotion by jointed, rigid legs
Laterally placed compound eyes
Complex, cuticular exoskeleton
Growth by ecdysis (molting)
No functional cilia
Coelom very reduced; body cavity a hemocoel
Open circulatory system
Jointed appendages on each body segment Sensory, Defense, Prey capture and manipulation,
Feeding, Locomotion, Respiration, Reproduction
Body organization
Rigid Exoskeleton
Extreme reduction of coelom
Muscle reorganization
Body cavity = hemocoel
Mineralized
cuticle:
Large crustaceans
Terrestrial Isopods
ARTHOPOD CUTICLE : Structure and Function
Water proofing
of epicuticle
C
A
Crustacean: thick & stiff
Insect: thin, strong & water repellant
B
Mechanisms for Hardening
1. Sclerotization (tanning)
2. Mineralization (calcite)
Figure 32.10 Ecdysis
Ecdysis
Incremental growth
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