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-colorless round body w/tapered ends

-w/ thick, flexible cuticle (outer coat) that is shed as it grows (ecdysis)

-well-developed digestive tract-pseudocoelom fluid distributes nutrients from gut to entire body

-distinctive thrashing movement (longitudinal muscles)

-important free-living decomposers in soils

-Most widespread of all animals:

-parasites in plants & animals

-located in muscle tissue

-trichina worm causes trichinosis (from eating undercooked pork)

-example of animal parasites:

-Phylum Nematoda: roundworms

*Ecdysozoans: Nematoda (exoskeleton secreted and shed periodically)

-"velvet worms"

-flexible cuticle w/ chitin

-segmented, but legs are soft & unjointed

-Ancient group close to arthropods

-marine forms back in Cambrian

-today: only in tropical forests

-Phylum Onychophora (segmented):

*Ecdysozoans: Onychophora

-segmented w/ stubby, lobe-like legs

-very small (

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-chelicerae for feeding (spiders w/ poison)

-body plan: cephalothorax + abdomen

-no antennae; simple eyes

-extinct eurypterid "water scorpion" was not a scorpion

-first ones were marine & f.w. eurypterids

-today, the only aquatic chelicerates are marine sea spiders and horseshoe crabs (not crabs)

-land predators or parasites

-1 pair pedipalps + 4 pair walking legs

-brown recluse

-black widow

>>predatory scorpions & spiders

>>parasitic ticks & mites

-a "vinegroon" or "whip scorpion" is not a scorpion

-"camel spider" or "sun spider" is not a camel & not a spider

>>other arachnids too

-arachnids include:

-spiders not only arthropods to make silk but they are only ones to use silk to capture

prey

-most chelicerates are arachnids

-Chelicerates

*Ecdysozoans: Arthropoda: Chelicerates

-many identical segments & legs

-mandibles for feeding; 1 pair antennae

-all terrestrial

-2 pair legs/segment

-millipedes are scavengers

-1 pair legs/segment; w/ "poison claws"

-centipedes are predators

-Myriapods

*Ecdysozoans: Arthropoda: Myriapods

-extremely successful on land; many in f.w.

-wings derived from cuticle extensions

-first animals to FLY

-body in 3 parts: head, thorax, abdomen

-thorax bears 3 pairs legs; 0-2 pair wings

-head with 1 pair antennae, compound eyes-mandibles for feeding

-complex organ systems, include unique Malphigian tubules for excretion of metabolic

waste

-anatomy:

-herbivores, predators, parasites, decomposers

-diverse feeding habits/ecological roles:

-some w/ complex social systems

-many do metamorphosis

-land-adapted reproduction

-huge human/ecological impact:

-Hexapods: Insects

*Ecdysozoans: Arthropoda: Hexapoda: Insects

*Ecdysozoans: Arthropoda: Crustaceans

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-mostly marine & f.w.; some land

-most are predators/scavengers

-have many branched legs on thorax & abdomen

-2 pair antennael feed w/ mandibles

-includes: lobsters, shrimp, crayfish, krill, crabs, barnacles, water-fleas & copepods, pillbugs,

sowbugs

-Crustaceans

-pentaradial symmetry as adults

-no head; no brain

-oral/aboral sides; central mouth

-Phylum Echinodermata

*Deuterostomes: Echinodermata

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