Ctenophora
How many ciliary plates do Ctenophores usually have?
8
What are the main morphological advantages of the Beroe that allows it to eat other jellies?
An enormous mouth that can stretch out and engulf entire jellies A complex gut to aid in digestion
What is the larval stage of Ctenophora?
Cydippid
Where are the sea walnuts native of?
North and South America
How are Ctenophora related to other animals?
Some evidence points towards them being a sister group related to Cnidara
If comb jellies are the most primitive animals, what does this imply about their nervous system?
That neurons were invented by ctenophores and then lost later on or there are two independent evolutions of the Nervous System
What is so interesting about the fact that comb jellies will eat off the tentacles of jellyfish?
They can incorporate the jellyfish's cnidae into the epidermis for its own defense
How was the population of the sea walnut brought back down to normal after it was introduced into the Black Sea?
When the Beroe jelly was accidently introduced into the sea as well they ate a lot of the over crowding sea walnuts, stabilizing the population and a regular level
What type of feeding behaviors do Ctenophores usually have?
heterotrophic
What are the muscles in Ctenophore derived from?
mesenchyme
How does sexual reproduction in ctenophores work?
most are hermaphroditic gonads are in the walls of the gut canal and when ready the gametes are shed via mouth into the open water were they either self or cross fertilize the zygotes created turn into cydippid larvae which grow into adults
How do ctenophores keep and change their shape?
muslces and elastic fibers that maintain and change shape
What is the nervous system of comb jellies like?
nerve nets but no brain or ganglia there is an apical organ that acts as a photoreceptor and a balance organ
How are comb jellies' nervous systems unlike those of bilateral animals?
no hox genes and some patterning genes only some synaptic function genes lack dopamine and epinephrine
How is food broken apart and digested in comb jellies?
pharyx chews the food digestive enzymes are secreted cilia mixes the contents of the gut up the digested food is passed through the meridonal canals to the rest of the body and through small pores into the mesenchyme excretion occurs through the mouth and anus
How does Cestus use its long flattened body?
possilby allows more nutrients to be taken up by from digestion since the whole body is basically the gut allows the animal to move quickly through the water may aid in catching and eating of prey
What are the three main systems that Ctenophores DON'T have?
respiratory excretory circulatory
How long have Ctenophora been around?
since Precambrian / Edicaran era
How are comb jellies' nervous systems similar to those of bilateral animals?
some neuronal fate and patterning genes present many synaptic genes present use of acetylcholine FMRFamide used vasopression used
What is the balance organ of the Ctenophora called?
statocyst
What happened after the sea walnut was introduced to the Black Sea?
the population boombed which drove down populations of fish and plankton almost washing out the other populations in the water the population got so dense that in 1989 there were 10 animals per cubis foot
What are the comb jellies famous for?
their population bursts that depress the levels of zooplankton and fish in the waters
How does the statocyst keep comb jellies upright?
there is a large calcium carbonate rock in the middle that if the animal tilts it activates the balancers which cause the cilia to move on the side of the tilt eventually evening out the animal again
Where are colloblast located?
they are lined up on the whole surface of the tentacle and surround the tentacle core
How does the sea walnut feed?
they are stealth predators they create water currents with cilia, trapping small prey in laminar flow and engulfing them when they get close enough
Do ctenophores have asexual reproduction?
they can regenerate really well, aseual reproduction is usually only seen if the animal is regrowing from peices
How do large-prey feeder ctenophores eat?
they consume parts of other animals or whole animals
What is the basic structure of a colloblast?
they have an elastic fiber filament that is simialr to a loaded spring, they have secretory granuoles that release a sticky substance when triggered there is a modified nucleus that runs down the whole colloblast
How do ctenophores move?
they have water near bouyancy but they do sink so they must swim, some have a flapping swimming they use
What is the function of a colloblast?
to discharge a sticky substance onto prey and get them stuck on the tentacles
How many cell layers do the bodies of Ctenophores usually have?
two
How do to plankton-feeder ctenophores eat?
use cilia to draw water towards them and past the tentacles once prey touches tentacles the colloblasts discharge and get stuck to prey the animal then wipes the tentacles over its mouth to get the food
How were the sea walnuts introduced to the Black Sea and when?
via ship ballast water in 1982
What do the sea walnuts eat?
zooplankton other comb jellies fish eggs larvae
