Diversity Invertebrate 2
Phylum Nematoda - roundworms
- Non-segmented (contrast annelids)
- Logitudinal muscle cords
- Alimentary canal (complete gu)
- No circulatory system
- Ubiquitous, Live in most habitats (e.g. water or soil)
- Free living or parasitic (e.g. pinworms or hookworms)
Arthropod Diversity
- Arthropods represent >85% of animal species
- 1018 individuals (10 quintrillion)
- 100,000,000,000,000,000,00
- 1.6 Billion per human
Phylum Arthropoda - jointed feet
- All arthropods have the following features:
1. Bilateral Symmetry
2. Segmented body
3. Hard exoskeleton
- Desiccation resistent
- Made of chitin
- Muscle attachment
- Molt (ecdysis)
4. Jointed legs
5. Many pairs of limbs
6. Complete gut
7. Open circulatory system
Arthropod Evolution
- Arthropods evolved from segmented worms
- Over time segments fused and began to specialize
Arthropod Diversity
- Cheliceriformes
- Chelicer: claw-like feeding appendage
- crabs, Horseshoe spiders, scorpions, ticks
- No sensory antennae
- Cephalothorax (fused head and thorax) and abdomen
- Myriapoda
- Millipedes: herbivores; 2 pairs walking legs per segment
- Emit hydrogen cyanide gas, monkey perfume
- Centipedes: carnivores; 1 pair walking legs per segment
- Hexapoda
- Hexapods are insects, which possess:
- 3 basic body parts (head, thorax, and abdomen)
- 3 pair of jointed legs
- 2 antennae
- Crustacea
- Crabs, shrimp, barnacles, lobster
- Marine and freshwater (a few terrestrial)
Phylum Ecinodermata- spiny skin
- Starsh, brittle stars, sea urchins, sea cucumbers, sea feathers
- Endoskeleton of calcareous plates
- Closely related to chordates
- Water vascular system: tube feet
- Adults have radial symmetry, larvae are bilateral
Water Vascular System
- Water Vascular system: hydraulic system of closed tubes lled with sea water;
used for locomotion, food/waste transport and respiration