BIOL 310 midterm

spherical body symmetry

any plane through body divides it in mirrored halves

good for floating and rolling

rare in animals, common for single celled organisms

radial body symmetry

2 planes through centre divids body into mirrored halves

biradial

only 2 planes produce mirroed halves

bilateral body symmetry

right and left mirroe halves along sagittal plane

great for forward movement

allows for head region

germ layer

distinct layer of cells that develop shortly after fusion of gametes

all tissues and organs develop from these

dipleblasts

2 germ layers

ectoderm and endoderm

triploblasts

3 germ layers

ectoderm, endoderm, mesoderm (muscles and curculatory system)

blastula

early cell divisions form a hollow ball of cells

deuterostomes

blastopore becomes anus

radial cleavage

protostomes

blastopore becomes mouth

spiral cleavage

body cavity (coelom)

internal space, tissues layers and embryonic development

allows organs to not be attached to outer wall (allows for movement)

schizocoely

division in mesoderm becomes coelom

schizocoely

enterocoely

cavity forms right away

deuterostomes

ecdysozoa

clade in the protostomes

includes those with a cuticle that is shed then replaced

lack cilia

embryos do not develop by spiral cleavage

spiralia

clade in the protostomes

animals developing mostly from spiral cleavage

panarthropoda

unranked clade in eudyzoa including phylum arthropoda, tardigrada, and onychophora

animals that molt, have segmented bodies, paired appendages with claws, and a brain

phylum arthropoda

segmented body (segments often fused to form tagmata)

hard outer cuticle made from protein and a polysaccaride called chitin

jointed appendages

arthropoda circulatory system

open circulatory system

fluid (haemolymph) pumped by heart into open spaces that surround organs and tissues

arthropoda gas exchange

across the body integument (outer covering) in some

others have gills or tracheal systems

subphylum crustacea

all appendages exept first antennae are biramous

2 pairs of anntenae

nauplius larvae

crustacea respiratory system

large crusts use featherlike gills

small crusts lack gills and have passive transfter across thin sections of body wall

terrestrial isopods have thin structure on ventral posterier that allows gas transfter (needs moistue)

crustacean circulatory systen

open system

hemolymph that contributes to gas transfer

crustacean excretory system

anterior to esophagus

called green glands

hydrostatic pressure of hemocoel forces fluid to filter into gland

resorption of salts and amino acids occurs as filtrate passes the excretory tubule and bladder

crustacean nervous system

fused ganglia throughout body

brain connects to eyes and 2 pairs of antennae

subesophageal ganglion connects to brain and suplies nerves to body

crustacean sense organs

compound eyes and statocycts (balance and equilibrium)

tactile bristles (setae)

remipedia

crustacean

primitive vermaform

predator

cephalocardia

crustacean

benthic marine detritavore

lack carapace, has cephalic sheild (head)

no eyes

branchiopoda

crustacean

mostly freshwater

may have carapace, appendages phyllopodous (leaf like)

many produce drought resistant eggs of zygotes

malacostraca

crustacean

may have carapace

body 19 or 20 segments

6-8-6 somite makeup

subclass eumalacostraca (order decapoda)

well developed carapace enclosing gill chamber

3 pairs of maxillipeds, 5 pairs of pereopods

one or more anterior pereopods are chelate (clawed)

carcinization

evolution towards carb like morphology

shortened abdomen

theostraca

branacles

reduced adult morphology

free-living and parasitic examples

hexapoda

6 legs

all legs uniramous (segments attach end to end without splitting)

3 body segments (tagmata) head thorax and abdomen

order collembola

class entognatha

small and terrestrial

no spiracles or thracheae (gas transfer across body wall)

insect larvae

true legs only on thorax

fleshy prolegs can occur on abdomen

metamorphasis

characteristic of clade ecdysozoa (common in arthorpods and hexapods)

exoskeleton shed between stages

ecdysis

molting

instar

each life stage between molts

ametabolous metamorphasis

slight changes or increase in size

found only in primitive wingless orders

hemimetabolous (incomplete) metamorphosis

gradual change

young are called nymphs (wingless)

wing pads in early instars where adult wings will grow

egg → nymph→adult

grasshopper, dragonfly

holomatabolous (complete) metamorphosis

about 88% of insects

larvae and adults often live in different environements and have different morphology

egg→larvae→pupa→adult

arthropoda subphyla

crustacea (lobsters, crabs)

hexapoda (insects)

myriapoda (centipedes, millipedes)

chelicerata (spiders, horseshoe crabs)

trilobita (extinct!!)

myriapoda

2 part body structure (head and multisegmented trunk)

uniramous multiarticulate appendages

head includes antennae, mandibles and maxillae

chelicerata

spiders, scorpions, ticks

2 part body plan: prosoma (7 segments) and opisthosoma (up to 12 segments+telson)

specialized appendages (chelicerae, pedipalps and 4 pairs of walking legs, antannae are absent)

class euchelicerata- subclass merstomata

modern horsehoe crab nearly unchanged from ancestors

unsegmented carapce covers body infront of broad abdomen and telson

5 pairs of walking legs

gills on ventral abdomen

carapace have 2 compound and 2 simple eyes

subclass arachnida

scorpians, spiders, ticks, mites

2 tagmata (prosoma and opisthosoma)

prosoma has carapace, pair of chelicera, pair of pedipalps, and 4 pairs of walking legs

opisthosoma lacks appendages

no antenna or mandibles

arachnida-acari (subclass arachnida)

ticks and mites

not monophyletic

complete fusion of body segments

anterior portion is caputulum, remaninder is idiosoma

family ixodide (ticks) (subclass arachnida)

hard ticks

sclerotized dorsal covering (scutum)

feeds on hosts for days to weeks, may carry disease

blood feeding ectoparasite with chelicerae for cutting skin

egg→6-legged larvae →8-legged nymph →adult

black legged tick (lyme disease) and dog tick in ontario

family argasidae (ticks) (subclass arachnida)

soft ticks, lack scutum

feed for short periods (>1 hour) may carry disease

ablypygi (subclass arachnida)

whip spiders

carapace, narrow pedicel, no telson, chelicerae specialized as fangs, pedipals raptorial

1st pair of appendages extented and sensory

uropygi (subclass arachnida)

whip scorpions and vinegaroons

carapace, whip-like telson (sensory), first walking legs elongated (sensory)

repugnatorial glands near anus spray acid at attackers

aranae (subclass arachnida)

carapace, chelicarae specialized as fangs (some have vemon), pedipaps modified as male copulatory organs

spinnerets produce silk

spider webs

fiborous protein

up to 4 pairs of abdominal spinnerets

producing web is energetically costly

some spiders use for catching prey others dont

scorpiones ((subclass arachnida)

carapace like sheild

3 body section (prosoma, mesosoma, metasoma)

large chelate pedipalps

spine-like telson with poison gland

pseudoscorpiones (subclass arachnida)

small

segmented carapace-like shield

chelicerae chelate with silk glands

phylum onychophora

ecdysozoa, evolutionarily between nematodes and arthropods

similar to arthropods, body cavity is a hemocoel divided into sinuses

cannot close spiracles, tracheal system evolved independently from arthropods

predaceous velvet worms

phylum nematoda

unsegmented roundworms

cuticle secreted by hypodermis, rigid and thick, made of collagen, must be molted

no circular muscles (only longitudinal) whip like movement

parasites, some free living (Caenorhabditis elegans)

complete gut, waste expelled by pseudocoelom pressue

gas exchange across body wall

nematode reproduction

amoeboid sperm crawls to female (sperm lack flagella)

Ascaris lumbricoides

intestinal roundworm

largest nematode infecting humans

female worm lays 200000 eggs a day

adults live in intestine, eggs released in feces

juveniles migrate through body

Dirofilaria immitis

dog heartworm

transmitted by mosquito bite

adults live in vessels around heart

annelida

segmented roundworms

secreted nonchitinous outer layer

annelid organ systems

complete digestive system

closed circulatory systems

complex nervous system

Eucoelomates

meristem(annelids)

independent movement of each segment

Subphylum Aclitellata: Class Polychaeta

paddle worms

mostly marine

paired paddle-like appendages called parapodia with chitinois hairs for movement

subphylum aclitellata: class polychaeta

sedentary forms live in tubes, suspension or deposit feeders

reporudce sexually by relasing eggs and sperm into water (oviparous)

marine forms have trochophore larvae, freshwater NO larval stage

subphylum chitellata: class oligochaeta

4 bundles of chaetae on each segment (few)

no larval stage

subphylum chitellata: class hirudinea

leeches

34 segments, anterior sucker and posterior sucker

ocelli (eye spots)

predatory leeches are nocturnal and negatively phototactic

subphylum chitellata: class branchiobdellida

ectosymbionts of crayfish

similar to leeches but only 11 segments and no anterior sucker

errantia

mostly free-moving annelids

traditionally called polychaetes

well differentiated head

parapodia sense organs