1. Biology, 9th ed, Sylvia Mader
Chapter 30
Chapter 30
More Invertebrates
More Invertebrates

2. Outline The coelom Molluscs Annelids Arthropods Echinoderms Bivalves
Cephalopods
Gastropods
Annelids
Arthropods
Crustaceans
Uniramians
Chelicerates
Echinoderms

3. Protostomes vs. deuterostomes
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

4. Protostomes Compared to Deuterostomes

5. Advantages of Coelom 2 Fate of blastopore 3 Coelom Formation
Mouth appears near blastopore in protostomes
Anus appears near blastopore in deuterstomes
3 Coelom Formation
Schizocoelom forms in protostomes
Enterocoelom forms in deuterstomes

6. 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 adapted for locomotion, attachment, or food capture

7. Body Plan of Mollusks

8. 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

9. Clams, oysters, mussels, and scallops
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

10. Bivalve Diversity

11. Tentacles and arms capture prey by adhesive secretions or suckers
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

12. Cephalopod Diversity

13. Have elongated, flattened foot Well-developed head region
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

14. Gastropod Diversity

15. Annelids Phylum Annelida are
Segmented partitions (septa) divide the well- developed, 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

16. Polychaete Diversity

17. Do not have well-developed head or parapodia
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

18. Earthworm, Lumbricus terrestris

19. Segmentaion evidenced by:
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

20. 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

21. Usually found in fresh water Same body plan as other annelids
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

22. Medicinal Leeches, Hirudo medicinalis

23. 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

24. Arthropod Skeleton and Eye

25. Three major arthropod subphyla
Variety of respiratory organs
Occurrence of metamorphosis
Three major arthropod subphyla
Crustaceans
Crayfish
Uniramians
Centipedes
Chelicerates
Spiders

26. 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

27. Crustacean Diversity

28. Male crayfish, Cambarus

29. Include insects, millipedes, and centipedes
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

30. Insect Diversity

31. Two Types of Insect Mouthparts

32. Female Grasshopper, Romalea

33. Centipede and Millipede

34. All appendages attached to cephalothorax; none on head
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

35. Chelicerate Diversity

36. 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

37. Echinoderms

38. Review The coelom Mollusks Annelids Arthropods Echinoderms Bivalves
Cephalopods
Gastropods
Annelids
Arthropods
Crustaceans
Uniramians
Chelicerates
Echinoderms

39. Biology, 9th ed, Sylvia Mader
Chapter 30
Ending Slide Chapter 30
More Invertebrates
More Invertebrates