Transcript Ch 30 Overview PowerPoint

Chapter 30
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Outline
The coelom
Molluscs
Bivalves
Cephalopods
Gastropods
Annelids
Arthropods
Crustaceans
Uniramians
Chelicerates
Echinoderms
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Advantages of Coelom
Protostomes vs. deuterostomes
Differentiated according to three major events in
embryological development
1 Cleavage
- Spiral cleavage in protostomes
- Radial cleavage in deuterostomes
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Protostomes Compared to Deuterostomes
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Advantages of Coelom
2 Fate of blastopore
- Mouth appears near blastopore in protostomes
- Anus appears near blastopore in deuterstomes
3 Coelom Formation
- Schizocoelom forms in protostomes
- Enterocoelom forms in deuterstomes
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Mollusks
Mollusks (phylum Mollusca)
Have three-part body plan
- Visceral Mass
 Contains
internal organs
- Mantle
 May
secrete shell and/or contribute to development of
gills or lungs
- Foot
 Muscle
capture
adapted for locomotion, attachment, or food
Body Plan of Mollusks
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Mollusks
Mollusks (cont.)
Nervous system consists of several ganglia
connected by nerve cords
Coelom is reduced, and largely limited to the
region around the heart
Heart pumps hemolymph through vessels into
hemocoel
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Bivalves
Clams, oysters, mussels, and scallops
Shell of two hinged parts, closed by powerful
muscles
No head, no radula
Circulatory system open
Sexes are separate
Ciliated gills hang down within mantle cavity on
either side of visceral mass
Beating of cilia causes water to enter cavity
Filter Feeders – capture tiny food particles
suspended in water
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Bivalve Diversity
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Cephalopods
Head Footed
Force water out mantle cavity
Tentacles and arms capture prey by adhesive
secretions or suckers
Beak used to tear prey apart
Well-developed sense organs
Closed circulatory system
Spermatophore packets passed from males to
females
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Cephalopod Diversity
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Gastropods, cont.
Have elongated, flattened foot
Well-developed head region
Eyes and tentacles project from coiled shell
Gills are found in mantle cavity in aquatic
gastropods
Mantle functions as lung in terrestrial gastropods
Gastropod Diversity
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Annelids
Phylum Annelida are
Segmented partitions (septa) divide the welldeveloped, fluid-filled coelom, which acts as
hydrostatic skeleton
Specialized digestive tract
Closed circulatory system
Ventral solid nerve cord
Most are marine
Setae (bristles) help in movement
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Polychaete Diversity
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Earthworms
Do not have well-developed head or parapodia
Setae protrude in pairs directly from surface of
body
Food drawn into mouth by action of muscular
pharynx
Digestion and absorption occur in long internal
intestine
- Typhlosole increases surface for absorption
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Earthworm, Lumbricus terrestris
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Earthworms
Segmentaion evidenced by:
Body rings
Coelom divided by septa
Setae on most segments
Gangli and lateral nerves in each segment
Nephridia in most segments
Branch blood vessels in each segment
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Earthworms
Reproduction
Hermaphroditic
Two worms lie in parallel to each other facing in
opposite directions
- Fused midbody segment (clitellum) secretes
mucus, protecting sperm from dessication
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Leeches
Usually found in fresh water
Same body plan as other annelids
No setae
Two additional suckers
- Some parasitic
- Keep blood flowing and prevent clotting by means
of hirudin, a powerful anticoagulant
Medicinal Leeches, Hirudo medicinalis
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Arthropods
Arthropods (phylum Arthropoda) have freely
movable jointed appendages
Very successful due to many characteristics
Rigid, jointed exoskeleton
- Must molt as they grow
Segmented, but some segments are fused into
regions
- Head, thorax, abdomen
Well-developed nervous system
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Arthropod Skeleton and Eye
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Arthropods
Variety of respiratory organs
Occurrence of metamorphosis
Three major arthropod subphyla
Crustaceans
- Crayfish
Uniramians
- Centipedes
Chelicerates
- Spiders
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Crustaceans
Decapods are the most familiar and numerous of
crustaceans
Shrimp, lobsters, crayfish, and crabs
Thorax bears five pairs of walking legs
Head and thorax fused into cephalothorax
- Covered by nonsegmented carapace
- Abdominal segments equipped with swimmerets
Respiratory system consists of gills
Crustacean Diversity
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Male crayfish, Cambarus
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Uniramians
Include insects, millipedes, and centipedes
Appendages attached to the thorax and abdomen
only have one branch
Head appendages include:
Only one pair of antennae
One pair of mandibles, and
One or two pairs of maxillae
Live on land and breathe by tracheae
Insect Diversity
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Two Types of Insect Mouthparts
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Female Grasshopper, Romalea
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Centipede and Millipede
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Chelicerates
Include terrestrial spiders, scorpions, ticks, mites,
horseshoe crabs and sea spiders
All appendages attached to cephalothorax; none
on head
First pair (chelicerae) are feeding organs
Second pair (pedipalps) function in feeding or
sensory
Chelicerate Diversity
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Echinoderms
Sea stars, sea urchins, sea cucumbers, and sea
lilies
Radial symmetry as adults (not as larvae)
Internal calcium-rich plates with spines
Central nerve ring with branches
Water vascular system for locomotion
Echinoderms
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Review
The coelom
Mollusks
Bivalves
Cephalopods
Gastropods
Annelids
Arthropods
Crustaceans
Uniramians
Chelicerates
Echinoderms
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Ending Slide Chapter 30
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