Lecture 26 Flashcards
What are the characteristics of the phylum annelida?
-bilateral symmetry -triploblastic -coelomate (unlike flatworms) -protostomes -body segmentation -serial repetition of functional units (unlike flatworms)
What is the annelid body plan like:
-coelom-acts as a fluid -filled (hydrostatic) skeleton -closed vascular system-transports vital gases, food and excretory products (greater potential for increased size) -ventral nervous system- nerve cord -movement- anatagonistic circular and longitudinal muscles (helped by parapodia or chaetae) nerve cord= runs ventrally two types of muscle= longitudinal and circular muscle, act antagonistically, help worms move closed vascular system= allows for larger size parapodia!
What are the characteristics of the phylum annelid class Polychaeta?
-marine worms -free-swimming and sedentary -have unjoined leg-like parapodia on every body segment -reproduction=mostly sexual via spawning or hypodermic impregnation, some species hermaphroditic -trocophore larvae-free swimming cilliated larva -mostly free swimming -release sperm and eggs into water and hope for the best hypordemic impregnation= inject sperm into the female larvae= look very different from the adult form
How are the segments functional?
in flatworms= segments= reproductive bits, can fall off be a new flatworm -here each segment contains the functional unit, nerve cells that operate, can’t chop it in half and survive =true segmentation
What are the characteristics of the phylum annelid subclass Oligochaeta?
-eg. earth worms -mostly terrestrial-live in soil, feed on organic matter -can grow very long (Gipsland earthworm upto 3 m) -hermaphrodites, but usually sexually reproduction -react to vibration -earth worms! -huge role in mantaining soil -when it rain= vibration= come up -there is a sport tapping fork on the ground
How do earthworms move?
they have to move through soil -chatea= to hold onto the ground -longitudinal muscles contract up (in one direction) and then the circular contract= squeeze and push= almost like peristalitic movement
What are the characteristics of the phylum annelid subclass Hirudinea?
-leeches -fresh water and terrestrial -mostly feed on vertebrate blood -saliva contains anti-coagulant proteins -have thermo-sensors to detect prey -coelum=usually reduced in size -segmentation=found in nervous and excretory system only -reproduction-internal fertilisation (some use hypodermic impregnation) blood clotting doesn’t work properly due to anti-coagulent -detect heat - coelum= not as much use as the intestine, as they might not get food as often so bigger gut=more can fit in -not wasting the eggs and sperm in the environment
Why do leeches have reduced segmentation?
more space for muscle and gut (smaller coelom) -movement= it has two suckers, anterior and posterior(for feeding as well, bigger) and it flips itself over and attach and flip over -intetsine-reduced segmentation -coelom= reduced -suckers= feeding, achoring and movement)
What are the characteristics of the phylum arthropoda?
-over 80% of all animals species -occupy all environments (marine, freshwater, terrestrial, subterranean, aerial) -enormous range of behaviours and body forms -split into 4 major sub-phyla -bilaterally symmetrical -triplobalstic -coelomate -protostome -body segmentation some also have= moult(part of the Ecdysozoa) and hard exterior (exoskeleton)
What are the characteristics of the sub-phylum of athropods the Chelicerata?
3 classes: 1.Scorpions and spiders (chelicerae are venomous) 2.sea spiders-marine; distantly related to spiders 3.Horseshoe crabs-marine; most primitive chelicerates (only surviving order within their class) -terrestrial and marine -four pairs of legs -lack antennae –have modified mouthparts= chelicerae
What are the characteristics of the sub-phylum of athropods the Myriapoda?
-centipedes and millipedes -myriapoda= many legs -head and segmented body -mandibles for feeding -usually compound eyes -terrestrial(live in leaf litter and soil) -centipedes= carnivorous -millipedes eat leaf matter -odd segments -myriapoda= many legs don’t have hundred legs -well defined head and segmented body, have hard exoskeleton, better protected than worms
What are the characteristics of the sub-phylum of athropods the Crustacea?
-mostly marine (few terrestrian= woodlice and slaters) -two pairs of antennae, biramous appendages -major component of plankton -mostly omnivorous; some filter feeders and some carnivorous -reproduction- sexes usually separate -unusual forms= the hermaphroditic barnacle -apendage at the bottom= split into two= like crabs =klepeta -major food source barnacle= like a shrimp lying on its back, sessile, hermaphroditic but usually reproduce sexually= longest penis relative to body size so can reach another individual= adaption to overcome problem
What are the characteristics of the sub-phylum of athropods the Hexapoda? (insecta)
-vast number of species and forms -mostly terrestrial -reproduction-mostly sexual, although some asexual -characterised by evolution of wings and flight -wing= stiff membrane of exoskeleton strengthened by veins -hexapoda= six legs -not as many marine as there the crustaceans are the dominant there so heaxapoda find their own nice= on land -unbranched(uniarmous) limbs -body divided into three section=head, thorax and abdomen -3 pairs of legs -specialised mouth parts -hard shell developed from the wing
How did the hexapoda develop flight?
-most likely evolved from gills in aquatic forms -traditionally though wings evolved from structures that would help gliding -evidence from stoneflies suggests early wings aid locomotion across water surface -most have two pairs of wings how wings evolved= look at stoneflies, have many species with all forms of wing evolution, at first help with swimming
PIC What are some examples of the insecta (hexapoda) mouthparts?
siphin= butterfly, moths sucking=mosquito fly= sponge, vomit on food and suck it up chewing= beetles
What is the advantage of Diversification of segmentation?
-body segment shows fusion and loss of segmentation to varying extents -some lost appendages as well -very different structures in each type look where legs are and how many of the three bits they have
Describe which have symmetry:
Germ layers?
Coelom?
Blastopore?
Segmentation?
