The Animal Kingdom

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The Animal Kingdom

• Mollusks, Arthropods, and Echinoderms
• Nancy G. Morris
• Volunteer State Community College

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Subgrade Coelomata Mollusks

• Includes chitons, oysters, clams,
• snails, slugs. octopus, squid
• General Characteristics
• molluscus soft body
• coelom greatly reduced
• main cavity is hemocoel - blood-filled cavity in
  open circulatory system
• show no segmentation
• bilateral symmetry obscure

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Subgrade Coelomata Mollusks

• Soft body composed of 3 main parts
• foot large muscular, usually ventral,
  locomotion
• 2) visceral mass contains digestive system,
  kidneys, heart, internal organs
• 3) mantle heavy folds of tissue which cover the
  visceral mass secrete shell form siphons,
  develop gill mouth

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Subgrade Coelomata Mollusks

• radula rasping, tongue-like organ found in all
  except bivalves
• trochophore larvum free-swimming links
  mollusks and annelids to a common flatworm
  ancestor

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Anatomyof a Clam
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Phylum Mollusca Classes

• Class Amphineura - chiton
• Class Bivvalvia - clams, oysters, mussels
• Class Cephalopoda squid, octopus, chambered
  nautilus
• Class Gastropoda snails, slugs, abalones,
  whelks, periwinkles, giant conch

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Review Animal Classification
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Phylum Mollusca Classes

• Class Amphineura -
• both nerves
• no eyes or tentacles
• marine
• elliptical, shell of 8 plates
• chiton

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Polyplacophora chiton
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Phylum Mollusca Classes

• Class Bivalvia -
• soft body between two halves of a hinged shell
• highly developed muscular foot
• bilateral symmetry obscured
• most marine, some fresh water
• no tentacles, head, radula
• clams, oysters, scallops, mussels

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Phylum Mollusca Classes

• Class Bivalvia -
• Pearl Production protective function foreign
  substance gets between mantle shell, mantle
  secretes pearly layers of nacre around substance
• clams, oysters, scallops, mussels

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Phylum Mollusca Classes

• Class Cephalopoda
• head foot
• shell reduced internalized in squid
• no shell in octopus
• largest invertebrates
• possess eyes and tentacles
• most active intelligent
• squid, octopus, chambered nautilus

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Phylum Mollusca Classes

• Class Cephalopoda
• most highly developed mollusk
• squid octopus possess ink sacs which produce
  melanin protective function
• head-foot arrangement forms a siphon through
  which water can be forcibly expelled producing
  jet propulsion
• squid, octopus, chambered nautilus

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Phylum Mollusca Classes

• Class Gastropoda
• stomach foot
• univalve single or one-piece shell
• some have no shell
• largest giant conch 1 foot length
• Urosalprix oyster drill bores hole in oyster
  digests
• snails, slugs, abalones, whelks, periwinkles,
  giant conch

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Phylum Onychophora

• missing link between annelids and arthropods ???
• Peripatus
• Figure 33.26 Campbell
• suggests a stage in evolution of arthropods from
  a segmented, coelomate ancestor common to both
  the annelids arthropods

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Phylum Onychophora

• Annelid characteristics
• segmentally arranged nephridia
• muscular body wall
• ciliated reproductive tract
• eye structure
• Arthropod characteristics
• tubular heart
• tracheae
• hemocoel
• large ganglion
• mouth parts modified appendages

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Subgrade Coelomata Phylum Arthropoda

• General Characteristics
• most successful and adaptable of all animals
• largest phylum in terms of numbers of species
• means jointed foot
• all have segmented bodies exhibit metamerism
• suggests a common ancestry w/annelids
• segments fused into specialized regions

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Subgrade Coelomata Arthropods

• General Characteristics
• Exoskeleton of chitin semi-rigid but flexible
  permeable to water waxy cuticle prevents
  dessication
• coelom hemocoel
• exhibit metamorphosis (change in form)
• exhibit molting (ecdysis)

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Trilobite fossil
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Phylum Arthropoda Classes

• Class Archnida -
• spiders, ticks, scorpions, mites
• arthropod w/ 8 legs

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Arachnids scorpion mites
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Phylum Arthropoda Classes

• Class Crustacea -
• lobsters, crayfish, shrimp, crabs
• Class Chilopoda -
• 100 leggers - centipeds 1 pr legs per segment
  carnivorous poisonous
• Class Diplopoda -
• 1000 leggers- millipedes 2 pr legs per
  segment herbivorous

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Crustraceans
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Diplopoda Millipede
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Anatomy of a Crayfish
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Phylum Arthropoda Classes

• Class Insecta -
• terrestrial aquatic insects
• Class Merostomata -
• horseshoe crab, king crabs thigh mouth

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Insect metamorphosis
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Limulus A living fossil
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Anatomy of a Grasshopper
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Subgrade Coelomata Echinoderms (Campbell p. 625)

• General Characteristics
• spiny skin
• all members marine
• exhibit secondary radiality (adults radials,
  but ancestors larval forms bilateral)
• bipinnaria larvum resembles hemichordate larvum
• nearest in relation to chordates

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Subgrade Coelomata Echinoderms

• General Characteristics
• endoskeleton w/ external spines or ossicles
• unique water vascular system for locomotion
• body parts in 5s or multiples of 5
• dioecious
• external fertilization

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Subgrade Coelomata Echinoderms

• General Characteristics
• no segmentation or well defined head region
• autotomy (self-amputation) survival mechanism
• regeneration
• no parasitic members
• deutrostomes (embrylogic development resembles
  chordates)

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Phylum Echinodermata Classes

• Class Asteroidea
• characterized by star
• starfish, sea stars
• Class Echinoidea
• characterized by spines
• sea urchins, sand dollars
• Class Holothuroidea
• characterized by whole
• sea cucumbers

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Echinoderms
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Sea Cucumber
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Echinoderm water vascular system

• bivium
• trivium
• madreporite
• stone canal
• ring canal
• radial canal
• ampulla
• ampulacral groove
• tube feet
• aboral
• oral

This is where you draw and label the essential
components of a starfish. The list on the left
should guide you.