BIO 202 Ecdysozoans: nematodes, Arthropoda 1

clade ecdysozoa

animals that molt a cuticle

cuticle

outer body covering

germ layers for nematoda

triploblastic, but pseudocoelomate

symmetry for nematoda

bilateral

protostome/deuterostome for nematoda

we don’t know

habitat of nematoda

marine, freshwater, terrestrial

skeletal system of nematoda

hydrostatic, using pseudocoelom

mode of feeding for nematoda

free-living and parasitic

mode of locomotion for nematoda

writhing, longitudinal muscles working against pseudocoel

circulation for nematoda

none

excretion/respiration for nematoda

excretory organ/ none; respiration only occurs through diffusion

reproduction for nematoda

sexual

distinguishing characteristics for nematoda

elastic cuticle, hydrostatic skeleton, only longitudinal muscles, writhe

adaptation for nematoda

wriggle though interstitial spaces

what phyla are represented in clade ecdysozoa

both coelomate and pseudocoelomate

why do phylum have the most constrained body plan

pressurized pseudocoel

what does the elastic cutucle contain

spacious pseudocoel under pressure

why do nematodes have only longitudinal muscles

to excel at moving through tight spaces; writher when removed from enivronment

what is special about nematodes

more than 20,000 species described; largest number of individual metazoans on the planet

what is hydrostatic pressure at

7 psi

nematoda have…

the most constrained body plan in all of metazoa

how do nematodes ingest their food

they swallow their food because the cuticle is a barrier

guinea worms

ingest eggs in contaminated water

cadueus

staff of hermes

what is the largest and most successful phylum

phylum arthropoda; more than 1 million species

what is the thick cuticle used for in phylum arthropoda

used as an exoskeleton

what is the cuticle made out of for phylum arthropoda

chitin + protein, limestone, wax

what do arthropod and nematodes undergo

ecdysis

ecdysis

cuticle must be molted to grow into exoskeleton

what do arthropods have

jointed appendages with muscles attaching from inside to exoskeleton

body plan for arthropoda

segmented (metameric) to form 3 regions; head, throax, abdomen

spiracles

tracheids with openings

how many layers does the cuticle have in phylum arthropoda

3

what is growth like in phylum arthropoda

is discrete

apodemes

allow flexion of articulated jointed appendages

what does exoskeleton mostly cover in phylum arthropoda

most of gut

what is the big surprise of molecular phylogenies of phylum arthropoda

insects are crustaceans

subphylum of phylum arthropoda

chelicerata, myriapoda, crustacea

subphylum chelicerata

better known for things they lack

what does subphylum chelicerata lack

no mandibles so they can’t chew food, no antennae on first segment, no appendage for sperm delivery

how do subphylum chelicerata respire

book gills or lungs

what marine classes are in subphylum chelicerata

merostomata (horseshoe crabs) and pycnogonida (sea spiders)

what terrestrial class are in subphylum chelicerata

class arachnida includes spiders, scorpions, ticks, and mites

how many appendages and pedipalps (walking legs) does subphylum chelicerata have

6 appendages and 4 pedipalps

how does class pycnogonida respire

diffusion

in class arachnida, what do book gills turn into

book lungs

digestion for class arachnida

extracorpeal digestion or suck fluids

spiders particularly successful in

production and manipulation of silk

specialized abdominal appendages

parachuting juveniles enhances dispersal

class diplopods

subphylum myriapoda; millipedes; 2 pairs of legs per segment; some squirt HCN

class chilopoda

subphylum myriapoda; centipedes; 1 pair of legs per segment

subphylum crustacea body plan

2 segments; cephalothorax and abdomen

biramous appendage

in subphylum crustacea; modified for many functions

what is the most primitive and earliest form of subphylum crustacea

nauplius larva