lec142

animals - characteristics

multicellular, heterotrophic, mobile, cell differentiation, sexual reproduction, blastula stage of development

body symmetry

asymmetric, radial, bilateral

coelomates

coelem and internal organs surrounded by mesoderm

coelom

fluid filled body cavity that contains organs

acoelomates

don't have enclosed body cavities between tissue layers

pseudocoelomates

fluid filled cavity which isn't surrounded by mesoderm

protostomes ?

mouth develops before anus

protostomes eg

mollusks, annelids, arthropods

protostome stages

2 layers of cells offset, solid masses of mesoderm tissue split to form coelem, mouth develops from blastopore

deuterostomes ?

anus develops before mouth

deuterostome eg

echinoderms, chordata

deuterostome process

2 layers of cells aligned, outward bulges of developing digestive tract form coelom, anus develops from blastopore

phylum porifera

sponges - pore bearing, mostly marine, sessile, free swimming larvae, no true tissues, flagellated collar cells, mostly hermaphrodite

cnidaria

stinging, aquatic, mostly marine, radial symmetry, 2 body forms - sessile polyps, mobile medusa, acoelomates

3 classes in cnidaria

jellyfish, hydra, sea anemones + corals

polyp reproduction

asexual - budding

medusa reproduction

sexual

coral reefs

formed by stony corals and symbiotic zooxanthellae, easily damaged

coral bleaching

they only tolerate a narrow temp range, if they go outside the range the symbiotic algae come out, polyp lose colour and can't survive

platyhelminthes

free living aquatic/parasitic, bilateral symmetry, acoelomates with parenchyma (spongy tissue). simple mouth, no anus, hermaphrodites, complex life cycle

platyhelminthes parasites

flatworms - ectoparasites of fish. flukes & tapeworms - endoparasites of mammals

platyhelminthes life cycle

pork tapeworm uses pig as secondary host and humans as primary host

adaptations for a parasitic life

small, flat/cylindrical shape, reduced sense organs, attachment organs, anaerobic respiration, hermaphroditic

taxonomy

science of naming and classifyinf organisms within groups

phylogeny

evolutionary history of a species/group

systematics

science of determining evolutionary relationships among organisms

criteria for classifying organisms

Morphological characters, fossil record, embryology, molecular analysis

homologous characters

result of common ancestry, more important for classification

analogous characters

convergent evolution, characters have evolved the same way because they are needed for the same purpose

primitive characters

traits inherited from a common ancestor that haven't changed much eg. milk in mammals

derived characters

trait which arose in most recent common ancestor of a lineage and was passed along to its descendants

systematics - phenetic system

groups organisms based on phenotypic similarity only, doesn't distinguish between homologous/analogous characteristics

classic evolutionary/cladistic systems

group organisms based on evolutionary relationships

classic system

all shared characters, primitive and derived characters, accepts mono and paraphyletic groups

cladistic system

derived characters most important, only monophyletic groups

cladogram

node position indicates relative time, branch length random

phylogram

branch length represent amount of change

dendrogram

nodes associated with geological time

monophyletic taxon

ancestor and all descendants

paraphyletic taxon

ancestor and not all descendants

polyphetic taxon

missing ancestors

parsimony

choosing simplest scientific explanation that fits the evidence

radiometric dating

comparing amounts of radioactive isotope with amount of decay products to estimate age

stratigraphy

layering of deposited rocks - timescale can be estimated

molecular clocks

amount of genetic divergence used to estimate timing

mollusc characteristics

bilateral symmetry, coelomates, mantle membrane secretes shell, muscular foot for locomotion, generally well developed head, radula for feeding, mostly aquatic, some terrestrial

classes within mollusca

gastropods, cephalopods, bivalves, chitons

bivalvia

clams, 2 shell valves, mostly sedentary or burrowing, aquatic, expanded gills for filter feeding

bivalvia fertilisation

separate sexes, external fertilisation, free swimming larvae

gastropoda

snails, terrestrial/aquatic, eyes, tentacles, asymmetric body due to shell coiling and torsion, herbivores, carnivores or scavengers

torsion

twisting of body in relation to head and foot brings anus above head

gastropoda reproduction

individuals have male and female genitalia, elaborate mating ritual, exchange sperm and a 'love dart', darter gains more fertilisations, darted dies sooner, both lay eggs

cephalopoda

octopi, squid - marine predators, integral head and foot, tentacles with suckers, brain in braincase, separate sexes and courtship displays

annelids

ringed - fanworms, bristle worms, earthworms, leeches - bilateral symmetry, coelomates, segmented body, body covered with chaetae, marine, freshwater and terrestrial, sexual reproduction, some can regenerate

chaetae

bristles used for movement

traditional classification - 3 annelid classes

polychaeta, oligochaeta, hirudinea

genetic analysis classification - 2 classes

errantia and sedentaria

errantia

mobile marine predators, crawl in seafloor, head with eyes and jaw, body segments, prominent parapodia, sexual reproduction and separate sexes

sedentaria

marine sedentary worms, earthworms (burrowers), leeches (ectoparasites/predators), lug/fanworms (filter feeders), small/no parapodia, few chaetae, regeneration, hermaphrodites

nematodes - main characteristics

bilateral symmetry, pseudocoelomates, tubular, non-antagonistic muscles, hydrostatic skeleton, free living/parasites, sexual reproduction, separate sexes

free living nematodes

marine/freshwater/terrestrial, live in all habitats, most are microscopic, important in soil nutrient cycling, most feed on bacteria and fungi in soil

parasitic nematodes

nearly all animal/plant groups have nematode parasites eg. elephantiasis is caused by filiariasis type nematodes and infects lymphatic system

potato cyst nematodes

globodera pallida, root feeders, important plant pest, destroys around 12% of crops annually

c. elegans

model for cell/developmental bio, first multicellular organism to have its genome sequenced, androdioecious - most are hermaphrodites but males can exist when stressed

nematoda species eg

roundworms , 25000 species described

echinoderms - main characteristics

deuterostome development, marine, coelomates, sexual reproduction, separate sexes, free swimming larvae

adult echinoderm symmetry

5 fold radial - pentamerous

larvae echinoderm symmetry

bilateral

echinoderm body plan

thin epidermis covering endoskeleton and external spines, water vascular system made of internal canals and external tube feet

what is the endoskeleton made of

calcareous plates and spines

function of water vascular system

feeding and locomotion

echinoderm species

sea lillies, urchins, cucumbers and starfish

arthropods main characteristics

bilateral symmetry, coelomates, exoskeleton, segmented body , paired jointed appendages, well developed body systems, sexual reproduction, separate sexes

exoskeleton

produced by epidermis, made of chitin and proteins

exoskeleton advantages

protection, prevents water loss, more efficient locomotion

exoskeleton disadvantages

limits growth, gas exchange and movement

gas exchange - small organisms

through the skin

gas exchange - aquatic/crustacean

gills

gas exchange - terrestrial/scorpions/spiders

book lungs - internal cavity, oxygen diffuses directly into blood

gas exchange - terrestrial/insects/millipedes

tracheae

sensorial organs

mechanoreceptors (touch and vibrations), chemoreceptors (smell and taste), photoreceptors (ocelli & compound eyes)

reproduction in arthropods

most species - internal fertilsation, horseshoe crab - external fertilisation, mating happens through direct/indirect sperm transfer

subphylum myriapoda species

millipedes and centipedes

myriapoda characteristics

terrestrial, waxy waterproof epicuticle, trachaea, separate sexes, internal fertilisation

myriapoda body parts

head with 1 pair antennae and mandibles, simple eyes, body has many segments, jointed appendages - millipedes have 2 pairs of legs per segment, centipedes have 1

crustacea subphylum species

shrimps, crabs, copepods, water fleas

crustacea characteristics

all aquatic except woodlice, gill gas exchange, procuticle with CaCO3, compound and simple eyes, separate sexes

crustacea reproduction

internal/external fertilisation, seminal receptacle in females, females lay eggs then carry them til they hatch

chelicerata species

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

chelicerata characteristics

terrestrial (except horseshoe crabs), gas exchange by book lungs/trachea (gills in horseshoe crabs), separate sexes, usually indirect sperm transfer, sophisticated mating and parental care behaviours

chelicerata body parts

divided into cephalothorax (head and thorax) and abdomen, 4 pairs of marching legs, no antenna, simple and compound eyes, chelicerae, pedipalps

chelicerae

fangs

pedipalps

sensorial

chelicerata sperm transfer

uses spermatophore - has a sac which contains the sperm, has an aperture mechanism to open it, transferred to females body

harvestmen body

without waist, visibly segmented, long legs

ticks/mites body

body without waist, not visibly segmented

hexapod head

1 pair antenna, mouthparts, 1 pair compound eyes, simple eyes

hexapod thorax

3 pairs legs, 2 pairs wings

hexapod abdomen

digestive system, stigmata and trachea - gas exchange, sexual organs

hexapod reproduction

internal fertilisation, sexual organs for direct sperm transfer, sexual dimorphism - male fighting, female oviposition (laying eggs), courtship rituals and nuptial gifts