Annelids Flashcards
what are the roles of parapodia?
- gas exchange (gills)
- movement (when supported with acicula)
- protection
- creating currents
describe an annelid’s nervous + sensory system
- each segment has 2 ganglia bundles
- has 2 ventral nerve cordc
- brain with eyes (cerebral ganglia)
what two phylogenic groups are within Clitellata (terrestrial and freshwater)?
Oligochaeta (earthworms) and Hirudenea (leeches)
how does Chaetopteridae feed?
- uses fin parapodia to create current inside tube
- current pulls water into tube from anterior end and organic matter into mucus bag
how does a metanephridium work?
1) ciliated funnel pulls coelomic fluid into coelom as primary urine
3) muscle contractions push primary urine through metanephridia
4) final urine exits through nephridiopores
what is inside an annelid segment?
- 2 metanephridia and a nephridiopore
- coelom
- blood vessels
- nerve cord
- peritoneum that compartmentalizes each segment
what are the differences between a protonephridium and a metanephridium?
proto:
- unicellular
- one opening (exterior)
- waste enters via flame cells
- fluid moved via cilia-generated currents
- contains a flame cell and flagella/cilia
- uses extracellular fluid as medium
meta:
- multicellular
- two openings (one to coelom one to exterior)
- waste enters via blood vessels
- fluid moved via muscular contractions
- uses coelomic fluid as medium
how do Echiurans feed?
- suspension and deposit feeding via mucus nets and proboscis that scoops and collects food
- adult burrows
what is the peristomium?
first segment behind prostomium
How does Siboglinidae feed?
- uses bacteria to collect material from hydrothermic vents
- chemoautotrophic
- no gut or mouth due to this
what families are under the class Sedentaria?
- Sabellidae (feathery mucus suspension)
- Echiura (no parapodia, chaetae, has single coelom)
- Capitellidae (surface deposit)
- Arenicolidea (subsurface deposit)
- Terebellidae (surface deposit)
- Siboglinidae (tubeworm, chemoautotroph, no mouth)
- Serpulidae (hard tubed suspension)
- Cirratulidae (organic tubed suspension)
- Spionidae (deposit + suspension)
how does Tomopteridae feed?
- uses elongated cirri and parapodia to swim and catch large prey in water column
what are acicula made of?
chitin
what are some features from Oligochaetes?
- no parapodia
- peristaltic movement
- gas exchange via skin
- pair of metanephridia at each segment
- no eyes
- simultaneous gamete exchange
- hermaphrodite
what similarities and differences do Cirratellidae and Serpulidae have?
- both suspension feeders using mucus net
- Cirratellidae = organic tubes, Serpulidae = calcified tubes
what are the body layers of annelids?
cuticle, epidermis, muscle, peritoneum (lines the coelom)
or
ectoderm, mesoderm, endoderm
how do Annelids move?
- sinusoidal motion (alternation of constricting and relaxing of R+L longitudinal muscles)
- peristaltic motion (alternation of constricting and relaxing circular muscles)
what feature defines Clitellata?
clitellum (banded reproductive organ)
how does Terebellidae feed?
- spaghetti worms
- bury trunk into sediment and uses tentacles/palps to reach out and grab food items
what is the pygidium?
terminal segment with anus
what are the three sections of annelids?
prostomium (head), trunk (body), pygidium (rear segment)
how would you describe the metameristic body plan annelids have?
repeating similarly shaped segments separated internally by septa (mesoderm)
how does Sipunculida feed?
- typically burrows
- anterior cilia plumage funnels food from surface
what characteristics do Clitellata have?
- reduction/loss of segments
- reduction of chaetae and parapodia
- specialization of segments
what trait distinguishes annelids from previous phyla (porifora, cnidarians and ctenophores)?
complete guts and coeloms
what families are included in the class Errantia?
- Nereidae (scavenger, can farm algae)
- Lumbrineridae (burrower, jaws resemble insect pinchers)
- Polynoida (carnivore, scaleworm)
- Glyceridae (burrower, 4 jaws)
- Tomopteridae (carnivore)
what traits distinguish Errantia from Sedentaria?
- larger parapodia + chaetae with acicula
- more developed head region and cephalization
- adapted pharyngeal structures (i.e jaws) for predating
what is a trochophore larva?
- swimming larva with a band of cilia around its midline
- blastophore forms mouth first, anus second
what is epitoky and how does it work?
- asexual reproduction
- parent worm releases buds/segments that develop into reproducing individuals
- new individuals (epitokes) swarm, release gametes then die
what symmetry do annelids have?
bilateral
describe briefly what a worm’s skeletal structure is like
coela separated by septa that hydrostatically supports frame
how does Arenicolidae feed?
- body is burrowed head down
- pharynx takes in sediment and expels non organic matter through anus
how do Sabellidae, Cirratellidae and Serpulidae feed?
- feather duster worms
- suspension feeding using mucus from ciliated tentacles on anterior
- cilia creates current that pulls organic matter onto mucus
how does Glyceridae feed?
- hunting (predatory)
- has 4 jaws
- has poison glands
what other classes are included in Annelida?
- Sipuncula (peanut worms, no segments, parapodia or chaetae, only 2 coelom)
- Chaetopteridae (burrowers, mucus food bag)
what two Sedentaria families are closely related to Clitellata?
Echiura and Capitellidae
How were Siboglinidae determined to be polychaetes?
had stubby parapodia with chaetae and L/R pairs of coela
what is the prostomium?
part of the head in front of the mouth
