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
How do insects develop in their lives?
-metamorphosis -egg-larva(catepillar)- pupa-adult -endopterygotes (subclass of insects) go through radical changes during ecdysis -have very different larval, pupal and adult stages -inside wing, can’t see till adult -changes in feeding, young= carnivorous often and then adults= herbivores
What are the 5 reasons why arthropods are so successful?
- Exoskeleton 2. Diversification of segmentation 3. Diversification of appendages 4. Advanced nervous system 5. Advanced sensory structures
What is the advantage of Exoskeleton?
-composed of chitin -make up of hardened plates separated by soft membranes (permits movement) -protection, support for muscles, prevent of water loss, can be adapted for unusual uses -it is like body armour -support for wings= muscles can attach -against dessication like the catepillar= has to get rid of the shit smell, so it accumulates the shit inside, then fires it out so it’s not that close
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
How do endopterygotes develop?
-metamorphosis -series of laval stages or nymphs -mouting (shedding of the exoskeleton) occurs between each stage -one type= nymphal so each is just small version of the adult but not fully developed, can see the wing but not devloped till last stage
What is the advantage of Diversification of appendages?
-many body segments bear different types of joined appendages -whip scorpion= for catching prey crab= for swimming
What is the advantage of an advanced nervous system?
-vison and knowing where you are moths can detect pheromones of females a kilometer away
What is the advantage of advanced sensory structures?
eg. compound eye, antennae…
Are most insects small?
-yes -largest living beetle is the Titan beetle (like a hand big) -fossils of dragonflies etc had 2 foot wingspan
Describe which have symmetry:
Germ layers?
Coelom?
Blastopore?
Segmentation?
