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Aurelia :- kzitem.info/door/PLMqIs0gPtGXjVzjwDvfooaQVwL1W3oz6L&si=t0NIcXprWf_JY1Df
Lower invertebrate bsc 1st semester:- kzitem.info/door/PLMqIs0gPtGXgsiMuhZI1vJ1Ztl7u5jUnW&si=5c_QyMHdf1pjwpmT
Notes:-
Digestive system of Aurelia
(Jellyfish) part- 3.
1.Gastrovascular canal
system
2. Nutrition
a. Food
b. Ingestion
c. Digestion
d. Distribution
e. Reserve food
1.Gastrovascular canal system
The rectangular mouth leads into a short gullet, within manubrium, which
opens into a spacious four-lobed stomach occupying the center of the
umbrella.
Extending laterally from the stomach are four wide interradial gastric
pouches. Within each gastric pouches is a C-shaped gonad and arrow of
small gastric filaments or phacellae, bearing nematocysts.
The gullet communicates with each gastric pouch through a groove-like
gastro-genital canal that runs between the two free ends of the gonad.
Around each gonad runs an exhalent channel that also communicates with
the gullet through the gastro-oral canal.
Radial canals branch out from pouches to join the circular or ring canal in
the bell margin.
From the periphery of the stomach as well as from the gastric pouches,
sixteen radial canals originate, four are per-radials, four inter-radials, and
eight adradials.
Both per radials and inter-radials are branched, while the adradials are un-
branched.
All the radial canals are lined by ciliated gastrodermis, which ultimately
open into a ring or circular canal situated at the margin of the body.
2. Nutrition
a. Food
Aurelia is exclusively carnivorous. It is mainly a suspension or ciliary feeder.
It feeds upon the planktonic organisms and small marine invertebrates,
such as crustaceans, worms, their eggs, and larvae.
b. Ingestion
The small planktonic organisms are carried directly into the stomach with
the entering water current.
Some small organisms that may get entangled in the mucus of the sub-
umbrellar surface are collected by oral arms.
Sometimes, as medusa sinks slowly or swims gently downwards, the prey is
captured in contact with tentacles and oral arms.
Nematocysts of oral arms paralyze and entangle these organisms, which are
then swept up along the lateral tracts of oral arms and passed into the
mouth.
Undesirable particles are rejected and dropped on the way.
If the prey, still in living condition, reaches the gastric pouches, it is
paralyzed and killed by the nematocysts of gastric filaments.
c. Digestion
The digestion takes place in the stomach and gastric pouches, where the gland cells of
these regions secrete enzymes for the extracellular digestion of protein, fats,
carbohydrates, and even chitin.
Partly digested food particles, circulate through the canal system and are ingested by
gastrodermal cells for intracellular digestion in food vacuoles.
The undigested material passes out of the body with the outgoing current of water.
d. Distribution
The water circulating through the canal system transports digested food to the
gastrodermis of all parts. Further, wandering amoeboid cells in mesogloea transports
food from the gastrodermis to the epidermis.
e. Reserve food
The food is reserved in the gastrodermal cells of gastric filament in the form of glycogen
and fat droplets.
e. Reserve food
The food is reserved in the gastrodermal cells of gastric filament in the form of glycogen
and fat droplets.
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Негізгі бет Digestive system of aurelia | digestion in aurelia | gastrovascular canal system | bsc 1st sem notes
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