Animal diversity 3 - The Protostomes (Annelida, Mollusca, Arthropoda) Key concepts What are the distinguishing characters and life histories of the Annelida, Mollusca, Arthropoda? There are LOTS more species in Arthropoda than in any other phylum Learn what distinguishes the three subphyla of arthropods: Chelicerata (scorpions, spiders & mites), Crustacea (lobsters, crabs, sowbugs & shrimp), Uniramia (insects, millipedes, centipedes) Not sure what you can do with a biology degree? Attend the Biology Career Series and investigate careers related to biology! Our Biology Career Events give students the chance to hear from a panel of professionals working in diverse positions. They include a time for questions & answers, and an informal dinner that allows students to network with the panelists! Biology Career Series: Health and Medical Careers! Thursday, February 9th 5:30 PM Life Sciences South, Room 440 Free and open to all interested! RSVP to Jennifer Cubeta at cubeta@email.arizona.edu or 621-1073. But first from last time How long can hatched Schistosoma eggs survive to infect snails? Appears to be only about 24 h Latest on Trichinella and trichinosis Not in cattle Human-human transmission highly unlikely In recent years, almost all cases have been from wild game A very few cases from recent Asian immigrants - no trichinosis in Asia, so consumption of rare or raw pork not uncommon Diversity of Annelida Examples of annelids? Earthworms, Polychaete worms (mostly marine forms), Leeches Diversity of Annelida Morphology Coelom - true coelom or pseudocoelom? Segmentation of body and coelom True coelom! Head w/ brain - more sophisticated nervous system Mesoderm lines body cavity and surrounds gut Diversity of Annelida Feeding Earthworms? Organic material in soil Polychaete worms? Parasites/predators/scavengers Respiration across body wall
Leeches? blood! (mostly) Medicinal leeches blood letting popular for centuries, fell out of favor in mid 1800s recently leeches found to be very useful in reattaching severed tissues anticoagulant in saliva prevents clotting, allows veins to re-grow better than synthetic compounds which act throughout the body, have side effects Very diverse - 110,000 species (compare to ~ 30,000 vertebrates) Examples? Examples of mollusks without shells? Examples of mollusks without shells include some of the most beautiful of all animals, the slugs (the marine sea slugs - nudibranchs) What s the meaning of all the bright colors? Nudibranch defense with nematocysts
Mollusca: Morphology Key adaptations the mantle & the radula The mantle - sheet of skin Secretes shell (when there is one), forms gills for gas exchange, and in cephalopods forms muscular cavity that forcibly ejects water for locomotion Mollusca: Morphology Key adaptations the mantle & the radula The radula - a hardened tongue Probably evolved for scraping algae off rocks, and in different species has been modified for puncturing, slicing, manipulating food Feeding niches Mostly grazers (e.g. snails on algae) or predacious Feeding niches Mostly grazers (e.g. snails on algae) or predacious amazing mollusk predators, the cephalopods (Video segment) Cephalopods Cuttlefish Cephalopods Nautilus Squid Octopus
The cephalopods (e.g. squid, cuttlefish, octopus, nautilus) I. Giant squid - 60 ft long -the largest invertebrate Diversity of Mollusca Giant squid Long been a subject of seafarers folklore 2004 - the first observations ever of a giant squid in the wild! The cephalopods (e.g. squid, cuttlefish, octopus) i. Giant squid - 60 ft long - the largest invertebrate ii. giant axons - most highly developed nervous system of invertebrates iii. chromatophores - allow sudden color changes for disguise, confusion and courtship iv. cephalopod intelligence - jointed feet Some examples? General morphology Jointed appendages
General morphology Jointed appendages Body is segmented General morphology Jointed appendages Body segmented External (or exo-) skeleton What s an exoskeleton good for? What are its drawbacks? Diversity of Arthropoda Limits to size Three subphyla* - Chelicerata, Crustacea, & Uniramia Chelicerata - scorpions, spiders & mites *(your book calls them phyla)
Chelicerata - scorpions, spiders & mites Morphology First set of appendages modified into pincers or fangs Feeding niches Mostly predatory but mites do almost everything - herbivores, predators, parasites Crustacea & Uniramia First appendages antennae Crustacea are the dominant marine arthropods any terrestrial crustaceans? sowbugs