Protosomes

Protosomes

moutjh first (not universal)

triploblastic

anterior brain

ventral nervous system

two clades of protosomes

Spiralia

mostly aquatic

spiral clevage

cilia or contractions

two clades of protosomes

ecdysozoans

cuticle exoskeleton wrom like

molt to grow

chintin, ridgit appendages

Spilria

Flatworms (Platyhemithins)

Platzyoa

(flatworms and rotifers)

ino specialized gas exchange systemalizedd gas exchange system
-mouth opens into ‘blind sac’ digestive
tract
-free living species are cephalized
-most are internal parasites

spilria

platyzoa

rotifers

most are tiny, but with specialized
tiny with spexialized organs
-complete gut
-move via cilia
-many are unisexual, one group
(bdelloid rotifers) known only from
females

spirilia

lophotrocozoa

Brachiopods and phoronids have
lophophores

spirla

brachiopods

lophotrochozoa

solitary marine animals with two-part shells
-shell is not homologous with mollusk
bivalves (dorsal and ventral)

Phoronid

spirlia

(lophotrochozoa)

small, sessile, marine worms
-live in secreted tubes made of chitin

Bryozoans

lophotrochozoa

olonial, many small individuals are
produced asexually
-connected
strands of tissue
-sperm is released into water, eggs
fertilized internally

spirlia

lophotrochozoa

(ribbon worm or Nemertea)

complete gut
-fluid-filled cavity called rhynchocoel; inside hollow
-muscle contractions expel proboscis
explosively; may be armed with stylets and paralytic toxins
-mostly marinecm, some >20 m

Lophozoans

annelids

spirlia

segmented body → better control of
movement
-moist environments

annelids

lophotrophyate

Polychaetes

largest group
-most marine, filter feeders
-pogonophorans, deep-sea
hydrothermal vents

annelids (segemented worms)

Clitellates

freshwater or terrestrial
-Oligochaetes (e.g., earthworms) no
eyes, hermaphroditic
-Leeches use suckers to move, feed on
host blood

Mollusks

Lophotrochozoa

spirila

evolutionary radiation
-tripartite body plan

ecdysozoa

nematodes

roundworms

ayered cuticle
-gas & nutrients -- cuticle and gut
-abundant, universal
-C. elegans, genetic model

ecdysozoa

Tardigrades

limbs are domiante for ecysozoan

unjointed legs
-tiny, marine sands, water films
-dormant phase

waterbear

ecdysozoa

Onychophorans

-unjointed legs
-soft, segmented
-humid tropics

Arthropods

ecysozonas

most successful
-jointed appendages
-rigid exoskeleton
-four clades

arthropods

ecysozonas

a.) crustaeans

dominant marine animals
-body:
*head
*thorax
*abdomen

crab, pill bug

arthropods

ecysonas

b.) hexapods

dominant
-tracheae
-antennae
-no abdominal appendages
->10M species??

arthropods

ecysoznas

c.) Myriapods

many legs
-head and trunk
-centipedes: one pair/segment, predatory
-millipedes: two pairs/segment, scavengers &
herbivores

arthropods

ecysoznas

d.)Pterygota

immature stages: “instars”
-morphological change
-complete metamorphosis (80%)
-first flight

65
d. Chelicerates

(arachids, horseshoe crab, marine spider)

head appendages form mouthparts
-four pairs of legs
-three clades

chelicerates

Pycnogonids

marine

most are carnivorosu

chelieriates

arachids

abundant terrestrial animals
-spiders, mites, ticks, scorpions
-small adults emerge from eggs

cherlicates

horseshoe crabs

marien scavengers

morphologiccal evolution

changes in developmental genes adn pathways, not radical shifts