invertebrates : mollusca
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Transcript of invertebrates : mollusca
Phylum Mollusca
3cuttlefish Nautilus Giant squid Architeuthis
clam
chiton
snail
slug
octopus
scallop
CHARACTERISTICSCHARACTERISTICS Second largest phylum in the animal kingdom (80000 living species and 40000 fossil species) Soft bodied animalsBody: head, foot and visceral hump Microscopic to macroscopicThey include chitons, snails, slugs, clams, oysters, cuttlefish, squids, octopods, scaphopods, ……. Slow to active organisms Coelomate, triploplastic, unsegmented
Second largest phylum in the animal kingdom (80000 living species and 40000 fossil species) Soft bodied animalsBody: head, foot and visceral hump Microscopic to macroscopicThey include chitons, snails, slugs, clams, oysters, cuttlefish, squids, octopods, scaphopods, ……. Slow to active organisms Coelomate, triploplastic, unsegmented
Terrestrial, freshwater, or marine environments Occur in a wide variety of environments Have different modes of nutrition Bilateral symmetry, torsion and coiling in
gastropods True coelom is reduced Skin is soft and often secrets the exoskeleton
or the shell Respiration by one to many gills (ctenidia) Radula in most molluscs Circulatory system of open type (except
cephalopods)
Blood contains haemocyanin and amoebocytes The nervous system is composed of a nerve
ring around the oesophagus and two pairs of nerve cords Sense organs include tentacles, eye spots,
statocysts in foot and osphradia beside gillsExcretion by a pair of u- shaped metanephridia Molluscs are unisexual (dioecious) but some
are hermaphrodite (monoecious) Fertilization is mostly external and rarely
internal Development is direct (no larva) or indirect
through free swimming trochophore and/or veliger larvae
Economic importance of Mollusca
Human food
Pearls
Buttons
Decoration
Ship-worms
Intermediate hosts of some parasites
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Scallops coarsely ribbed food
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Destructive Burrow into wood
Shipworms
The soft edible parts of themolluscs represent an important
source of animal protein
The shells are used to manufacture beautiful gifts or to decorate the
furniture
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Characteristics of Phylum Mollusca
All organ systems are present, well-developed– Respiratory organs– Circulatory system, with heart
Greater body size possible
Freshwater clamSquid
GENERAL BODY PLANGENERAL BODY PLAN Head
Ventrally located muscular foot
Dorsally located visceral mass
Mantle / pallium – for shell/spicule secretion
Radula (except for bivalves)
Complete digestive tract
Gonads in visceral mass
Monoecious or dioecious
Head
Ventrally located muscular foot
Dorsally located visceral mass
Mantle / pallium – for shell/spicule secretion
Radula (except for bivalves)
Complete digestive tract
Gonads in visceral mass
Monoecious or dioecious
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Molluscan body form
2-part body plan:1. Head-foot2. Visceral mass
Octopus
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Mollusk Body Plan
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Head-footFoot:
ventral Muscular structure Locomotion Attachment modifications
Octopushttp://acolyte.org/images/octopus.png
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Head-foot
Snail radula
Head:– anterior– Cephalic sensory
organs– Feeding organs:
Radula– Most molluscs (not
bivalves)– rasping structure– Tongue-like– Rows backward-
pointing “teeth”– Scraping food– drilling
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Visceral mass Digestive organs Reproductive
organs Circulatory
organs Respiratory
organs
Mantle Attached to
visceral mass Dorsal skin folds protective In some, mantle
secretes protective shell over visceral mass
Chiton
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Mantle cavity– Space between
mantle and foot– Opens to outside– Functions:
Gas exchange (respiration)
Excretion/elimination
Release reproductive products
Subphylum Conchifera: with 1 shell; (-) spicules
1. Class Gastropoda2. Class Bivalvia3. Class Cephalopoda4. Class Scaphopoda5. Class Monoplacophora
Subphylum Aculifera: with multiple shell plates; (+) spicules1. Class Polyplacophora2. Class Aplacophora
Subphylum Conchifera: with 1 shell; (-) spicules
1. Class Gastropoda2. Class Bivalvia3. Class Cephalopoda4. Class Scaphopoda5. Class Monoplacophora
Subphylum Aculifera: with multiple shell plates; (+) spicules1. Class Polyplacophora2. Class Aplacophora
CLASSIFICATIONCLASSIFICATION
Class MonoplacophoraClass Monoplacophora
Bilaterally symmetricalHave a dorsal, single, dome- or
cap-shaped shellHas a broad, flattened footIncludes many fossil species
Bilaterally symmetricalHave a dorsal, single, dome- or
cap-shaped shellHas a broad, flattened footIncludes many fossil species
Neopilina Subphylum Conchifera;Class Monoplacophora
Neopilina Subphylum Conchifera;Class Monoplacophora
N. galatheae
Class AplacophoraClass Aplacophora
Worm-like molluscs called SOLENOGASTERS
With oblong, cylindrical to vermiform bodies
No shellLack a well-defined headRadula and jaws sometimes present
Worm-like molluscs called SOLENOGASTERS
With oblong, cylindrical to vermiform bodies
No shellLack a well-defined headRadula and jaws sometimes present
Neomenia Subphylum Aculifera;
Class Aplacophora
Neomenia Subphylum Aculifera;
Class Aplacophora
N. yamamotoi
Chaetoderma Subphylum Aculifera;
Class Aplacophora
Chaetoderma Subphylum Aculifera;
Class AplacophoraC. japonicum
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Classes of Mollusc
Chiton
Class Polyplacophora“many plate-
bearers”ChitonsDorsoventrally
flattenedShell= 8
overlapping dorsal plates
marineUnderside of
chiton
Class PolyplacophoraClass PolyplacophoraInclude marine chitons
Bodies elongated and dorsoventrally flattened
Shell divided into:–7 or 8 overlapping plates–Flat, creeping foot
Head reduced
No eyes
Well defined mouth with radula
Include marine chitons
Bodies elongated and dorsoventrally flattened
Shell divided into:–7 or 8 overlapping plates–Flat, creeping foot
Head reduced
No eyes
Well defined mouth with radula
Chiton Subphylum Aculifera;Class Polyplacophora
Chiton Subphylum Aculifera;Class Polyplacophora
C. glaucus
8 calcareous plates
girdle
Muscular foot
Acanthozostera Subphylum Aculifera;Class Polyplacophora
Acanthozostera Subphylum Aculifera;Class Polyplacophora
A. gemmata
Class GastropodaClass Gastropoda Members usually
sluggish and sedentary Mostly with
asymmetrical bodies Most with single,
conical and spiral shellMay be reduced or
absent (e.g. nudibranch) (+) Cephalic tentacles Simple eyes Radula Jaws Large, prominent foot
Members usually sluggish and sedentary Mostly with
asymmetrical bodies Most with single,
conical and spiral shellMay be reduced or
absent (e.g. nudibranch) (+) Cephalic tentacles Simple eyes Radula Jaws Large, prominent foot
eyespots
tentacles
jaws
RADULARADULA
toothed chitinous ribbon in the mouth of most molluscs used for cutting
and chewing food before it enters the esophagus It is present in all
molluscs except bivalves
toothed chitinous ribbon in the mouth of most molluscs used for cutting
and chewing food before it enters the esophagus It is present in all
molluscs except bivalves
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Class Gastropoda Well-developed sense organs
– Eyes at base or at end of tentacles
Major Changes from Generalized Mollusc
Development of head Dorsoventral elongation Shell – from shield to retreat Torsion Conispiral coiling and asymmetry
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Class Gastropoda
May have protective shell
TorsionWeight of shell over head, mantle
cavity posteriorTorsion – 180o counterclockwise
rotation of visceral mass, shell, mantle, mantle cavity
Occurs in larvae not adultFirst gastropodsDetorsion
Costs of Conispiral Shell
Loss of a gill, nephridium, atriumMantle cavity (anus and
nephridiopore) now anterior and near mouth
Compensation - changes in water flow or shell structure
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Coiling–Absent in some–Visceral mass/mantle may be
coiled–Successive coils- whorls–Caused pressure on right side
adaptation: loss of rt. kidney, auricle, gill Water enters via left, leaves right
LocomotionMost move using footMost have ciliated sole and
secretory glands (mucus producing)
Hard-bottom dwelling and terrestrial, and large soft-bottom snails - undulating wave of muscle contractions
FeedingMost often thought of as algal scrapers (radula)
Deposit feedersSuspension feedersScavengersPredatorsParasites
Turbo (turban snail) Subphylum Conchifera;
Class Gastropoda
Turbo (turban snail) Subphylum Conchifera;
Class Gastropoda
• Torsion• Whorl• Spire
• Torsion• Whorl• Spire
Cypraea (cowries) Subphylum Conchifera;
Class Gastropoda
Cypraea (cowries) Subphylum Conchifera;
Class Gastropoda
Shell uncoiled
Nudibranchsoft-bodied snailsNudibranchsoft-bodied snails
Spanish shawl
Spanish shawl
Sea slug
rhinophores
gills
Class BivalviaOysters, clams, mussels ~8,000 species
(1,300 freshwater, rest marine)Benthic filter-feeders (a few exceptions)
• No radula• Enlarged gills
Compressed bodyShell
Two valves Hinged dorsally Completely encloses body
Class Bivalvia / PelecypodaClass Bivalvia / Pelecypoda
Shells have 2 lateral valvesElastic ligamentBody is enclosed by a 2-lobed mantle
Shells have 2 lateral valvesElastic ligamentBody is enclosed by a 2-lobed mantle
(elevation)
Class Bivalvia / PelecypodaClass Bivalvia / Pelecypodahatchet shaped foot in burrowersHead lacks eyes, radula and tentacleshatchet shaped foot in burrowersHead lacks eyes, radula and tentacles
Freshwater clam
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Class Bivalvia
clams, oysters, mussels, scallops soft body between two halves of a hinged
shell
California musselGiant clam
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Class Bivalvia
Aquatic– most marine,
some fresh water no tentacles,
head, radula adductor muscle Large cilia-
covered gills (in most)
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Bivalve shell morphology
Umbo- oldest part of shell– Growth in concentric lines around it
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Valves open by adductor muscle– contraction= closed– relaxing= open
Hinge= mantle secretion of more protein, less calcium carbonate
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Water movement through bivalves
1. incurrent siphon - water into the mantle cavity
2. water circulates over the gills– Gas exchange– Filter feeding
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Locomotion Mostly sedentary/sessile highly developed muscular foot
– often to burrow into sediment– move by slicing-like motion of foot – swim by chattering motion of shell
(scallops)
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Oyster
lower valve is cemented to any object available
Improve water quality
Decrease bank erosion
food
http://www.csc.noaa.gov/scoysters/images/bio/oysters2.jpg
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Pearl Production
Developing pearl
Developing pearl
EpitheliumEpithelium
ShellShell
protective function– foreign substance
between mantle & shell
mantle secretes pearly layers of nacre around substance
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Giant Clam & Burrowing Clam
some= food
Giant clam
Siphon
Burrowing clam
Tridacna (giant clam) - Subphylum Conchifera;
Class Bivalvia
Tridacna (giant clam) - Subphylum Conchifera;
Class Bivalvia
Spondylus (scallop) Subphylum Conchifera;
Class Bivalvia
Spondylus (scallop) Subphylum Conchifera;
Class Bivalvia
S. versicolor
S. princeps
Chlamys (scallop) Subphylum Conchifera;
Class Bivalvia
Chlamys (scallop) Subphylum Conchifera;
Class Bivalvia
C. islandicus
C. swifti
Perna (mussel) Subphylum Conchifera;
Class Bivalvia
Perna (mussel) Subphylum Conchifera;
Class Bivalvia
P. veridis
Crassostrea (oyster) Subphylum Conchifera;
Class Bivalvia
Crassostrea (oyster) Subphylum Conchifera;
Class Bivalvia
Pacific oysters
Atlantic oyster
Anodonta (freshwater clam) – Subphylum Conchifera;
Class Bivalvia
Anodonta (freshwater clam) – Subphylum Conchifera;
Class Bivalvia
A. suborbiculata
A. anatina
Class CephalopodaClass Cephalopoda
Free-swimming Fast moving Active carnivores Elongated body Skeleton may be external, internal or absent Foot developed into prehensile arms or
tentacles
Free-swimming Fast moving Active carnivores Elongated body Skeleton may be external, internal or absent Foot developed into prehensile arms or
tentacles
Octopus arm
Class CephalopodaClass Cephalopoda Well-defined head
Complex eyes
Brain in cartilaginous cranium
(+) radula
Beak-like jaws
Tentacles surrounding mouth
Well-defined head
Complex eyes
Brain in cartilaginous cranium
(+) radula
Beak-like jaws
Tentacles surrounding mouth
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Class Cephalopoda squid, octopus, nautilus,
cuttlefishammonoids
“head foot” Largest, most complex
invertebrates
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most highly developed mollusc– Most active and intelligent
Marine predator– carnivorous
Cuttlefish
Cuttlefish camouflage
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shell reduced/absent & internalized (vestigal) (squid, octopus)
Nautilus- shell Cuttlefish- small, enclosed by mantle
Octopus
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head is well developed - large eyes – Complex eyes (except Nautilus)
Cornea, lens, chambers, retina, iris
Well-developed nervous system - complex brain
Squid
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foot is modified into multiple tentacles with suckers (in some)– Grasp prey– Taste via suckers– Crawling
siphon forces out water: “jet propulsion”
Octopus movement
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squid & octopus possess ink gland which produce melanin ; escape
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Octopus Eight arms with suckers Crawl or eject water from siphon Change skin color Most intelligent invertebrate
– Colorblind, but can be taught different shapes
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Octopus
camouflage
http://www.cephbase.utmb.edu/viddb/vidsrch3.cfm?ID=132&CephID=495
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Some octopi can kill humans: – Blue-ringed octopus
Size of golf ball Bacteria in salivary glands Paralysis, but victim fully conscious
Blue-ringed octopus
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Nautilus Up to 94
tentacles– No suckers
Shell with many gas chambers
Nautilus
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Ammonoids
Extinct– 400 to 65 MYA
Died out with dinosaurs
Loligo (squid) Subphylum Conchifera;
Class Cephalopoda
8 arms and 2 tentacles8 arms and 2 tentacles
mantle
siphon
ctenidia
Sepia (cuttlefish) Class Cephalopoda
Octopus (octopus) – Subphylum Conchifera;
Class Cephalopoda
Octopus (octopus) – Subphylum Conchifera;
Class Cephalopoda
Nautilus (nautiloid) – Subphylum Conchifera;
Class Cephalopoda
Nautilus (nautiloid) – Subphylum Conchifera;
Class Cephalopoda
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Circulatory system of molluscs
Open circulatory system (except Class Cephalopoda)– Open circulatory system
heart pumps hemolymph (blood) through body cavity, b/w cells
No small blood vessels
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Circulatory system of molluscs– Closed circulatory system (Class
Cephalopoda) Blood confined to vessels
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Molluscan reproduction
Mostly dioecious
http://www.biology.ualberta.ca/courses.hp/zool250/Labs/Lab08/Lab08.htm
Long-finned squid- Loligo
Giant squid
Class ScaphopodaClass Scaphopoda
Burrowing and sedentary Shell in one piece Shell opens on both sides With modified conical foot Head is reduced or absent No eyes With radula, jaws and thin tentacles
Burrowing and sedentary Shell in one piece Shell opens on both sides With modified conical foot Head is reduced or absent No eyes With radula, jaws and thin tentacles
Dentalium (Elephant’s tusk shell) Subphylum Conchifera;
Class Scaphopoda
Dentalium (Elephant’s tusk shell) Subphylum Conchifera;
Class Scaphopoda
shellshellanterior
posterior
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Class Scaphopoda– Tooth shells– Long, slender body– Burrows into mud– Shell open at both ends
http://www.ucmp.berkeley.edu/mollusca/scaphs/scaphopoda.html
Digestive system of mollusca
Nervous system of mollusca
Class: CephalopodaIt is a very diverse class, with 600 living species
and more than 7500 fossil species. The class, Cephalopoda, includes the
Chambered Nautilus, cuttlefish, squid, and octopus, as well as fossil ammonite and other fossil forms.
Size varies from planktonic to some as large as sixty feet; e.g., the present day squid, Architeuthis princeps, found in open ocean.
However, most cephalopods are small, and they form a major component of the food web of larger fish and whales.
Dibranchiata Tetrabranchiatae.g. Octopus, Sepia e.g. Nautilus
One pair of gills Two pairs of gills
One pair of kidneys Two pairs of kidneys
One pair of auricles Two pairs of auricles
The shell is internal or absent External large, thin, coiled shell
The arms are 8 to 10 arms, bearing suckers
Numerous tentacles without suckers
The funnel is simple and forms a complete tube
The funnel is formed of 2 lobes (not simple)
Order: Decapoda Order: Octopoda
e.g. Sepia, Loligo e.g. Octopus
Shell is internal Shell is absent
The body is elongated The body is globular
Has a pair of lateral fins Has no fins
8 arms and 2 long tentacles 8 arms
Arms provided with stalked suckers
Arms provided with sessile suckers
Echinoderms are a phylum of marine animals including the sea star and the sand dollar.
Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone.
The phylum contains about 7,000 living species.
The Echinoderms are important both biologically and geologically.
Phylum: Echinodermata
Echinoderms form a well-defined and highly-derived clade of metazoans.
They have attracted much attention due to their extensive fossil record, ecological importance in the marine realm, intriguing adult morphology, unusual biomechanical properties, and experimentally manipulable embryos.
The approximately 7,000 species of extant echinoderms fall into five well-defined clades: Crinoidea (sea lilies and feather stars), Ophiuroidea (basket stars and brittle stars), Asteroidea (starfishes), Echinoidea (sea urchins, sand dollars, and sea biscuits), and Holothuroidea (sea cucumbers).
Approximately 13,000 echinoderm species are known from the fossil record.
Introduction
Economic importance Most humans know the Echinoderms rather from the
unpleasant side: if one finds oneself near the coast, on a rocky shore or reef, one must beware the prick of a sea urchin.
However in the kitchens of some countries,echinoderms are regarded as a delicacy; and for children sea-urchin skeletons are as popular a collecting object as brightly coloured starfish are fascinating.
Around 50,000 tons of sea urchins are captured each year, the gonads of which are consumed particularly in Japan, Peru and in France. Sea cucumbers are also considered a delicacy in some countries of south east Asia.
It does appear that some sea cucumber toxins restrain the growth rate of tumour cells.
The calcareous tests or shells of echinoderms are used as a source of lime by farmers in areas where limestone is unavailable.
1. Five fold symmetry: arms or rays occurs in multiple of 5's.
2. Advanced Biological systems: --Digestive system including mouth, alimentary canal (intestine), and anus. --Water vascular system: hydraulic system which driven by water and muscular contraction serve to motion of tube feet. These tube feet, small structures with sucker-like endings, provide for locomotion and or feeding. -- Reproductive system -- Nervous system -- Skeleton made of CaCO3 which is developed as discrete plates or segments, each comprising a single crystal of calcite. This monocrystalline structure is particularly illustrated in the structure of spines of the urchins.
Characters
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