Ch. 32 bio

• · Mostly terrestrial or marine
• · Lack antennae
• · Body consists of cephalothorax and abdomen (most)
• · Six pairs of appendages:
• § 1 pair chelicerae – claw-like feeding appendages
• § 1 pair pedipalps – sensory structures
• § 4 pairs walking legs

(horseshoe crabs, spiders, scorpions, harvestmen, mites, ticks)

one pair of legs per segment; carnivorous

two pairs of legs per segment; herbivorous

• · Terrestrial
• · Body divided into head and trunk
• · Head with mandibles and antennae ( 1 pair )Body with many legs

exhibit 4 life stages [egg à larva à pupa à adult]

exhibit 3 life stages [egg à nymph à adult]

• · Dominant terrestrial arthropods
• · Body has 3 sections: head, thorax and abdomen
• · Antennae (1 pair)
• · Mouthparts – mandibles modified for chewing , sucking, sponging, or lapping
• · Three pairs of legs on thorax
• · Two pairs of wings ( most )
• · Breath via tracheae – unique to insects; open to outside via spiracles
• · Exoskeleton periodically molted.

( dragonflies, grasshoppers, true bugs, mantophasma, beetle, flies, bees, butterflies)

• · Mostly marine and freshwater
• · Body of most with 2 sections: cephalothorax and abdomen
• · Appendages on thorax and abdomen
• · Two pairs of antennae
• · Mandibles as mouthparts
• · Dioecious ( most)
• · Nauplius larva
• -krill- main food item of baleen whales

(crabs, crayfish and lobsters, shrimps, krill, copepods, isopods, barnacles)

• Crustacea
• Hexapoda
• Myriapoda
• Chelicerata

earliest authropods to evolve

segmented bodies, hard exoskeleton and jointed appendages.

• · Jointed appendages
• · Coelomate (reduced as a hemocoel)
• · Segmented body
• · Exoskeleton composed of protein and chitin (provides protection and waterproofing; must be molted)
• · Muscles attached to exoskeleton
• · Well-developed sensory organs
• · Open circulatory system – hemolymph percolates through hemocoel.

pinworms, hookworms, Filarial worms – cause elephantiasis, trichinella spiralis – causes trichinosis

inhibit plant growth, reduce yields and distort root structure.

• · Ubiquitous
• · Free-living or parasitic
• · Unsegmented body; tapered at both ends
• · Pseudocoelomate
• · Thick cuticle (shed 4 times)
• · Complete digestive tract
• · Longitudinal muscles
• · Dioecious ( Female are larger than male)

• Nematoda (roundworms)
• Arthropoda (“jointed feet”)

• Marine
• · Head surrounded by grasping tentacles, usually with suckers
• · Shell external, internal or lacking
• · Mouth with or without radula
• · Only mollusks with closed circulatory system
• · Locomotion by jet propulsion using siphon (modified foot)
• · Predators

• · Marine, freshwater, terrestrial
• · Head present
• · Coiled shell (most)
• · Many are monoecious
• · Foot used for locomotion
• · Have radula

• · Marine and freshwater
• · Hinged, laterally flattened shell
• · Mantle forms incurrent and excurrent siphons
• · Reduced head
• · No radula
• · Filter feeders

squid, octopus, cuttlefish, nautilus

slugs, snails

clams

• · Marine
• · Shell with 8 plates
• · Foot used for locomotion
• · Radula used to scrape algae from rocks

• Polyplacophora (chitons)
• Bivalvia
• Gastropoda (aposmatic coloration)
• Cephalopoda

• · Coelomate (reduced)
• · Mostly marine
• · Most have an open circulatory system and a hard shell of calcium carbonate
• · Body has 3 main parts: foot, visceral mass and mantle
• · Most are dioecious
• · Trochophore larval stage in marine mollusks