Annelids Flashcards
Phylum Annelida are L..
Lophotrophophores
are annelids coelomates?
yes
define Coelomate
cavity fully lined with peritoneum
lating name for ring?
annulus
defining characteristic of annellida
one of more pairs of chitonous chaetae/ (key-tee)
there are 17,000 species of annelida , true or false?
true
what length can they grow to?
1mm-3m
largest earth worm?
gipsland earthworm
what is the basic annelid organisation?
METAMERISM = THE MAIN BODY IS COMPOSED OF A REGION OF REPEATED UNITS (SEGMENTATION
what are the three parts of the annelida body plan?
- head 2. segmented trunk 3. pygidium
what is the Pygidium
the posterior of the annelid where new segements are created - this is how the worms grow.
define metamerism
the serial repition of segments and organ systems . segments are seperated by septa. segment growth comes from the pygidium
are annelids schizocoelic?
yes
3 advantages of being schizocoelic
- gut seperated from the body wall and with its own musclulature can move independently (can bend without pushing food along inside the gut.
- coelom provides a space where gametes can mature and nutrients and waste products can be moved or stored
- hydrostatic skeleton upon which muscles can act
define hydrostatic skelton
what lines the coelomic cavity?
peritoneum
define mesothelium
an epithelium made of mesoderm
what has the body wall got?
cuticle, epidermis, connective tissue dermis and muscle layer derived from coelomic lining
i toughen up the body wall and resist bulges what am i?
cuticle fibres in the wall
i am bundles of chitonous, thin walled cylinders held together by sclerotinized protein, produced by epithelial cells , what am i?
Chaetae (key-tee)
do annelids have a brain?
they have anterior dorsal brain located in protomium and a ventral pair of longitudinal nerve cords
what is the prostomium
the head
did my eyes evolve independently from the arthropods?
yes
how do i poop as an annelid?
with a metanephridia that draws fluid in from the coelom
how does the blood get ‘pumped’ with no heart?
using the muscles. using contractions in the dorsal blood vessel. it is a closed circulatory system
how do annelids reproduce?
all forms of asexual reprodution are present - fragmentation, budding and transverse fission
(spiral cleavage and in polychaetaes develop into a trochophore larva.
defining characteristc of Class Polychaeta?
paired lateral outfoldings of the body wall (parapodia?)
defining characteristic of Class Clitellata
pronounced cylindrical glandular region of the boody (clitellum) that plays important roles in reproduction
2. permanent gonads
what are the two subclasses of Class Clitellata?
subclass Oligochaeta and subclass Hirudinea
(earthworms and leeches)
70% of annelids are in this class and nearly all live in marine environments what am i
polychaetae
(poly - keet)
how many pairs of eyes do polychaeta have?
one
do polychaetes have tentacles?
yes - one pair of appendages on the prostomium
where is the neuropodia?
closest to the ventral nerves
parapodia is good for?
locomotion and gas exchange
what kind of muscles do polychaete have
circular AND longitudinal muscles
a hydrostatic skelton requires 4 things…
- cavity housing an incompressible fluid that transmits pressure changes uniformly in all directions
- cavity is surrounded by a flexible outer body membrane. (for deforming)
- that the volume remains constant in the cavity
- the ability for the animal to attach itself to the substrat for progressive locomotion
when my segments are long, which muscle is contracting?
circular muscles (sideways
when when my segments are short, which muscle is contracting
longitudinal
polychaetes can me divided into two groups…
- errant species ( active, mobile)
2.sedentary species
how do errant species move?
circular muscle play a minor role. longitudinal muscle antagonise those on the other side - rapid eel like movements
imagine oars (parapodia) and power strokes are the shovelling
i dont have any parapodia and have complex feather like appendages - what type group of polychaete am i from?
Sedentray
what are the 4 type of feeding in Polychaetes?
- non-selective
- selective deposit feeders
- raptorial feeding (jaws)
- filter feeding
define non-selective feeding
eat mud or sand and show
little discrimination in the size or type of particles eaten.
define non-selective feeding
use palps or buccal organs to sort
material from the sediment before ingestion.
define raptorial feeding
use their proboscis to seize their food
items
define filter feeding
collect particles suspended in the water
column.
how do polychaetes reproduce?
exclusivley sexual in most species , most gonochoristic but all hermaphrodites
define epitoke
the formation of a pelagic, reproductive individual from a benthic, non-reproductive invidual - in benthic comunnities
Epitoky is a process that occurs in many species of polychaete marine worms wherein a sexually immature worm is modified or transformed into a sexually mature worm. Epitokes are pelagic morphs capable of sexual reproduction
two ways Epitoky occurs?
- Epigamy
2.Schizogamy
define Epigamy
the whole worm. mature worm undergoes MTMP swarm and dies
define Schizogamy
modification of posterior segments as a stolon, they detach and die
polychaete development is done by spiral cleavage yes or no?
yes
define spiral cleavage
the process by which cells of the early embryo divide and spiral around the pole-to-pole axis of the embryo – is the most common mode of animal development
