1. Invertebrates Phylum Annelida
Segmented Worms
segmentation allows specialization of system
Body Plan: Tube-within-a-tube
Body Systems
Digestion
Pharynx, esophagus, crop, gizzard, intestine, accessory glands
Musculatory
Longitudinal and circular muscles in each segment
Circulatory
Closed system with pumping hearts
Nervous system
brain, ventral nerve cord, and ganglia in each segment
Excretory system
nephridia in most segments

2. Annelida cont’d Class Polychaeta Largest class - marine worms
Have setae-bristles for anchoring worm or helping in locomotion
Arranged in bundles on parapodia
Swimming, gas exchange
Polychaetes are seasonal breeders
After fertilization, a trochophore larva develops-same larval type as molluscs

3. Annelida cont’d Class Polychaeta cont’d Representative Organisms
Clam worms-Nereis
Predators-eat crustaceans and other small animals
Tube worms
Tentacles that form a funnel-shaped fan
Sessile filter feeders

4. Polychaete diversity
Fig

5. Annelida cont’d Class Oligochaeta Earthworms Few setae per segment
No obvious head
Gas exchange across body wall
Feed on leaves and other organic matter
Food is drawn into mouth by muscular movements
Digestive tract has a large surface area
Typhlosole-expanded region on dorsal surface of intestine

6. Earthworm, Lumbricus
Fig

7. Annelida cont’d Class Oligochaeta cont’d Segmentation Structure
External - evident by body rings
Internal - septa
Nervous System
Ventral nerve cord has ganglionic swellings in each segment
Lateral nerves extend from ganglions
Excretory
Paired nephridia in each segment
1st funnel-like collects coelomic fluid
2nd exits through body wall

8. Annelida cont’d Class Oligochaeta cont’d Segmentation cont’d
Circulation
Blood moves anteriorly through dorsal vessel
Enters aortic arches- “hearts”
Pump blood to ventral vessel
blood then moves posteriorly
Branches in each segment

9. Annelida cont’d Class Oligochaeta cont’d Reproduction in earthworms
Hermaphroditic
Male organs- testes, seminal vesicles, sperm ducts
Female organs-ovaries, oviducts, seminal receptacles
Worms lie parallel in opposite directions
Clitellum produces mucus to keep sperm moist
After separation, produces a slime tube which moves eggs and sperm together for fertilization
Slime tube then produces a cocoon

10. Annelida cont’d Class Hirudinea Leeches Most live in freshwater
Most are ectoparasites- have suckers for feeding
Saliva contains hirudin-anticoagulant
Have same general body plan as other annelids
Lack setae
Each body ring has transverse grooves
Makes leech appear to have more segments

11. Invertebrates Phylum Arthropoda
Exoskeleton of chitin
Must undergo molting to allow growth
Exhibit jointed appendages
Walking, swimming, reproduction, eating, sensory reception
3 body regions
Head, thorax, abdomen
Well-developed nervous system
Brain and ventral nerve cord
Sense organs-compound eyes, antennae

12. Arthropod diversity
Fig

13. Phylum Arthropoda cont’d.
Subphylum Crustacea
Barnacles, shrimps, lobsters, crabs, crayfish
Terrestrial - sowbug

14. Phylum Arthropoda cont’d.
Subphylum Crustacea cont’d
Crayfish: Representative external structure
Fused cephalothorax
Head has compound eyes and 5 pairs of appendages
First 2 pairs are antennae, 3 pair are mouth parts
Thorax has 5 pair of appendages-walking legs
1st walking leg has a pinching claw
Gills are situated above the walking legs
Abdomen- has swimmerets
Last 2 segments have uropods and telson

15. Phylum Arthropoda cont’d.
Subphylum Crustacea cont’d
Crayfish: Representative internal structure
Digestive system
2 part stomach, green glands for waste excretion
Vascular system
heart pumps blood with hemocyanin into hemocoel
Hemocyanin has blue pigment
Hemolymph flows around organs

16. Phylum Arthropoda cont’d.
Subphylum Crustacea cont’d
Crayfish: Representative internal structure cont’d
Nervous system
Brain and ventral nerve cord with segmental ganglia
Sensitive hair like receptors on antennae
Mechanoreceptors: responds to physical stimuli
Chemoreceptors: sensitive to chemicals in the water
Reproduction
Sexes separate- sperm transfer by first pair of swimmerets
Ovaries open at base of third walking legs
After fertilization, eggs attach to swimmerets of female

17. Male crayfish, Cambarus
Fig

18. Phylum Arthropoda cont’d.
Subphylum Uniramia
Insects; largest and most diverse group
General structure
Head with pair of compound eyes or several simple eyes, a pair of antennae, mouthparts adapted to specific way of life
Thorax: 3 pairs of legs and wings if present
Abdomen: contains internal organs

19. Phylum Arthropoda cont’d.
Subphylum Uniramia cont’d
Representative Organism: Grasshopper
3rd pair of legs is adapted for jumping
2 pairs of wings
Tympanum on side of first segment of abdomen
Ovipositor of females- for digging a hole in which to lay eggs.

20. Phylum Arthropoda cont’d.
Subphylum Uniramia cont’d
Grasshopper cont’d.
Internal organs
Digestive system-stomach, intestine, rectum, anus
Excretory system - Malpighian tubules
Uric acid-nitrogenous waste
Respiratory system-spiracles lead into trachae
Air pumped by contraction and relaxation of body wall
Circulatory system-heart pumps hemolymph into aorta, leads to a hemocoel
Hemolymph has no specialized pigment and is colorless

21. Phylum Arthropoda cont’d.
Subphylum Uniramia cont’d
Grasshopper cont’d.
Reproduction
Adapted to terrestrial life
Internal fertilization protects zygotes and gametes from drying
Penis inserted into female, sperm stored in seminal receptacle
Fertilized eggs are deposited into ground
Metamorphosis
change in form and physiology that occurs as a larva becomes and adult
Immature grasshopper called nymph

22. Female grasshoppers
Fig

23. Phylum Arthropoda cont’d.
Comparing Subphyla Uniramia and Crustacea
Grasshopper: terrestrial
Spiracles and trachae for gas exchange
O2 diffuses directly through to reach cells
Has tympanum for reception of sound
Use legs for hopping and wings for flying
Penis for passing sperm to female to prevent drying
Crayfish: aquatic
Crayfish gills for gas exchange
require oxygen-carrying pigment to carry oxygen to cells
Hair like receptors
Utilize uropods for swimming
Sperm passed to female, eggs carried externally.

24. Phylum Arthropoda cont’d.
Subphylum Chelicerata
Arachnids: Spiders, ticks, scorpions, mites
Cephalothorax
6 pairs of appendages
Chelicerae, pedipalps, and 4 pairs of walking legs
Abdomen contains internal organs
Ticks and mites are ectoparasites

25. Phylum Arthropoda cont’d.
Subphylum Chelicerata cont’d
Representative Organism: Spiders
Narrow waist separates cephalothorax from abdomen
Fangs deliver poison to prey
Pedipalps sense and hold prey
Digestion:
Digestive juices released into prey, initial digestion is external
digested “broth” then is sucked into stomach
Gas Exchange
lamellae of inner body wall for gas exchange
“book lungs”
Silk glands for web-spinning

26. Arachnid diversity
Fig