2. Phylogeny of Arthropods Arthropoda Worm-like Ancestor Trilobites (extinct) Annelids (worms) Onychophorans (worms w/legs) Chelicerates (spiders) Crustaceans (lobsters) Insects (butterflies)

3. General Characteristics metamerism (segmented body) jointed appendages bilateral symmetry secreted exoskeleton ecdysis (molting) open circulatory system ventral nerve cord and brain

4. DIVERSITY Numbers about 80% of all animals are arthropods estimated to be over 30 million arthropods far more of them than all other metazoan species combined in virtually every conceivable environment: marine, terrestrial, freshwater, and aerial habitats. Phylum Arthropoda Subphylum Trilobita (extinct) Subphylum Chelicerata Subphylum Crustacea Subphylum Uniramia (insects)

5. Phylum Arthropoda Subphylum Trilobita (extinct) Subphylum Chelicerata Subphylum Crustacea Subphylum Uniramia (insects)

6. NERVOUS SYSTEM

7. Open Circulatory System Doral heart surrounded by pericardial sinus Blood (hemolymph) enters heart through ostia (openings) pumped through arteries Hemolymph- colorless; contains hemocyanin Hemocoel- blood cavity

8. Open Circulatory System

9. Compound Eye Facet Lens Crystalline cone Pigment cells Visual cells Nerve fibers from visual cells Optic nerve Ommatidia

10. 1. General most arthropods are gonochoric fertilization may be external or internal in aquatic arthropods always internal in terrestrial species 2. Sperm Transfer sperm transfer usually by mating or copulation females usually store the sperm in a seminal receptacle REPRODUCTION

11. Subphylum Trilobita 521-250 mya Earliest arthropod

12. Trilobite eye

13. Subphylum Chelicerata xiphosurans (horseshoe crabs), arachnids, sea spiders mostly terrestrial cephalothorax-abdomen 6 pairs cephalothoracic appendages chelicerae, pedipalps, 4 pairs legs no antennae

14. a. Xiphosura (horseshoe crab, Limulus polyphemus) b. Arachnida most chelicerates are arachnids several taxa (orders), many are common and familiar SCORPIONES (scorpions ) ARANAE (spiders ) OPILIONES (harvestmen, daddy longlegs ) PSEUDOSCORPIONES (pseudoscorpions) ACARINI (mites and ticks ) c. Pycnogonida (the giant sea spider, Colossendeis australis) Subphylum Chelicerata

15. Limulus is a benthic scavenger and predator. Prey include clams and other invertebrates that it digs for in the sand. The tail spine is used as a self-righting mechanism if the animal is overturned accidentally. Lives up to 19 years Reaches sexual maturity at about 9 to 12 years old Horseshoe Crab Limulus polyphemus, Carcinoscorpius rotunda, and Tachypleus gigas.

16. Mates during spring and summer full and new moons, onto ocean beaches. Females lay up to 30 thousand eggs, which males fertilize before burying them in the sand Horseshoe Crab

19. Arachnid

20. a heterogeneous taxon with many subtaxa two pairs antennae marine, freshwater, and terrestrial Primarily aquatic Free-floating larval stage 26,000+ known species Subphylum Crustacea

21. ANOSTRACA fairy shrimp and brine shrimp PHYLLOPODA tadpole shrimps, ostracod, water fleas MALACOSTRACA the largest, most heterogeneous, and diverse crustacean taxon shrimps, crabs, lobsters, mantis shrimps, pillbugs, crayfishes COPEPODA copepods enormous ecological importance as planktonic herbivores CIRRIPEDIA barnacles Subphylum Crustacea

22. Arthropod Development Zoea MegalopsNauplius

23. Gills a. General gills are evaginations typical of aquatic animals blood is oxygenated by gills oxygen delivered to tissues by blood b. Crustacean Gills crustacean gills are usually associated with appendages blood circulates through the gill and is oxygenated c. Book Lungs present in many arachnid orders similar to book gills of horseshoe crabs oxygen transport from the lungs to the tissues is by blood Respiration

24. Subphylum Uniramia

26. Decorator Crab Sponge crab Camouflage

27. Camouflage: anemone crab

28. coral guard crabs and pocilloporid corals

29. gall crabs and pocilloporid corals

30. scarlet cleaner shrimp

31. sea cucumber crab and sea cucumbers

32. pompom crabs and sea anemones