Annelids Two Flashcards
features of sedentaria?
live in tubes/burrows segmented body plan parapodia small or absent - interfere with burrowing head has tentacles many have gills
features of oligochaeta?
~3000 freshwater and terrestrial - few marine few short setae no sensory appendages on protosmium clitellum - secretes mucous during copulation and forms a cocoon
how do oligochaeta move?
constriction of circular muscles pushes them forward, constriction of longitudinal muscles pulls trailing segments forward
bristles anchor the segments to prevent backward sliding
how do oligochaeta reproduce?
simultaneous hermaphrodites
bodys align and sperm exchanged, cocoon slides forward and collects eggs from oviduct and sperm from seminal tract - cocoon slips of and ends close
fertilisation and development occur in cocoon
how do oligochaeta feed?
deposit feeders
consume soil - the muscular walls of the pharynx act like a suction pump to draw in food
muscular gizzard grinds up food - contains grit ingested for this job
digested in intestine
why are earthworms so important?
aerate the soil - greater depth for roots
improves fertility of soil - castings filled with minerals/nutrients taken to the surface
features of hirudinea?
leeches
freshwater mainly
thick muscular bodies - usually flattened dorsalventrally
anterior/posterior suckers
no parapodia/head appendages/setae
segmented but no septa
coelom filled with connective tissue and muscle
how do leeches move?
don’t generate peristaltic waves as no septa
move by using suckers as temporary anchors - using circular and longitudinal muscles
how do hirudinae feed?
sanguivorous - feed on blood
sensory organs on head and body which detects changes in light intensity
three feeding types;
needle like proboscis and secrete hemetin which stops blood clots
jaws - y shaped incision releasing anaesthetic so feed undetected - hirudin stops clotting
jawless - swallow prey whole
why are leeches used medicinally?
blood letting olden days
now used to reduce fluid pressure following damage to vascular tissue
used to re-attach limbs, leeches drain excess blood until venous system can re-establish
how do leeches reproduce?
sim herm
cross fertilisation during copulation
clitellum only visible in breeding season - secretes a cocoon which recieves fertilised eggs attached to submerged object or body
features of polychaeta?
ingest sediment and extract nutrients from organic matter
lug worms - L shaped burrow, water passes through using peristalic movements
sediment ingested and stripped of organic material, rest expelled
other types of feeding in polychaeata?
deposit - tentacles find food - extended by ciliary action and retracted by muscles
epithelium of tentacles secretes mucous coat - organic material sticks
tentacles transports food to mouth by cilia
suspension - particles removed from water by radioles, as water passes over tentacles its driven between pinnules by cilia slowing water flow and facilitating extraction of suspended particles which are carried along grooves by cilia
ingested if small, sand stored
features of siboglinidae?
marine
live in long chitinous tubes usually at depths greater than 200m - hydrothermal vents
how do siboglinidae feed?
absorb through tentacles - no mouth or anus
mutualistic association with chemautotrophic bacteria - oxidise hyrdogen sulphide or methane to provide energy for production of organic compounds
