Download 1) Write about Hydra. Ans-In Hydra, body is cylindrical and

FAQs
1) Write about Hydra.
Ans-In Hydra, body is cylindrical and measuring about 1.3 cm in length.Anterior end
contains mouth or hypostome, which is crowned with 6 to 10 filiform nematocyst
bearing tentacles. Proximal end of the body contains pedal or basal disc or foot
meant for attachment to the substratum. Body is diploblastic, consisting of outer
ectoderm, inner endoderm and intervening mesogloea. Body wall encloses a
gastrovascular cavity extending into the tentacles.
2) Write the position of testes and ovaries in male and female Hydra
resectively.
Ans- In female Hydra, ovary and buds are found on sides in mid position. In
male Hydra 3 or 4 pairs of testes, are found anteriorly and has a fullly grown
bud with tentacles on side. Testes are developed near the oral end and ovaries
near the base.
3) Give a detailed account on reproduction in Hydra.
Ans- It reproduces sexually by fusion of sperms and ova. During asexual
reproduction, lateral buds develop on the sides of the body which later on
detach and develop into new Hydra .
4) Add a note on colony Of Obelia.
Ans- The colony of Obelia looks like a delicate, mossy or fur-like growth, whitish
or light brown. It consists of horizontal and vertical filaments. The basal or
horizontal anchoring portion of a colony is like a creeping root or complicated
meshwork, encrusting over the surface of the substratum. It is called the
hydrorhiza or rhizome (Gr., rhizo, root). The hydrorhiza gives off several
slender, upright or vertical threads, called hydrocauli. Each hydrocaulus forms the
main stem or axis of a colony and measures about 2 to 3 cm in height.
5) Write the position of mouth in polyp and medusa stage of Obelia in its
lifecycle.
Ans- During the polyp stage, the mouth is situated at the top of the body,
surrounded by tentacles, whereas during the medusa stage, the mouth is situated at
the distal end of the main body structure..
6) What is Scyphistoma.
Ans- In the life cycle of Aurelia, elongated larva metamorphose into a small
trumpt-shaped or hydra like polyp, about 5mm high, without perisarc known as
Scyphistoma.
7) Mention the division of body pattern in Sea-anemone.
Ans- Body is divided in to three regions in Sea-anemone like-pedal disc, column
and oral disc.
8) Write the distribution of Gorgonia.
Ans-It is found in South Atlantic and West Indies, Indo-Pacific ocean, Malay
Archipelago, Bermuda and Bahamas .
9) Add a note on Polyps or anthocodia in Gorgonia.
Ans-In Gorgonia polyps or anthocodia emerge from branches and contain 8
pinnate tentacles, mouth, gastrovascular cavity, 8 gastric filaments and
mesenteries. Polyps occur in rows and on two sides only of the stem and its
branches.-.
10)
Write about pedal disc in Gorgonia.
Ans- In Gorgonia the base of the colony is expanded to form a hold fast organ
called as pedal disk.