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1. DR. HARI SINGH GOUR CENTRAL UNVIERSITY SAGAR (M.P.) Topic – Coelenterate – Aurelia & Physalia DEPARTMENT OF ZOOLOGY SUBMITTED BY Name YAMINI YADAV REG NO. Y20265028 Sub – M.Sc. I Invertebrates Practical DATE 08/04/2021 Signature SUBMITTED TO DR. DIVYA RAWAT

2. PHYLUM COELENTERATE - AURELIA

3. Habit, Habitat and Structure of Aurelia Aurita • Aurelia Aurita is a commonest jelly-fish or moon-jelly, occurs in coastal waters of tropical and temperate oceans of the world close to the surface of water. It is cosmopolitan in distribution. It lives either singly or in large groups found floating or swimming freely. It is carnivorous and reproduces both by asexual and sexual methods.

4. Shape, Size and Colour • he medusa of Aurelia Aurita is flattened, bowl or saucer-shaped gelatinous structure called the bell or umbrella. It exhibits tetramerous radial symmetry. It usually measures about 7.5-10 cm in diameter, though much larger forms (up to 30 cm in diameter) have also been recorded from Atlantic coast. It is almost transparent having bluish-white body with pinkish gonads. • (ii) External Structures: • The bell or umbrella is distinctly divided into a slightly convex upper surface and a concave lower surface; the convex surface is known as exumbrellar surface and the concave surface is known as subumbrellar surface. The margin of umbrella is circular which is broken by eight notches. Each notch is provided with a pair of marginal lappets enclosing sense organ called tentaculocyst or rhopalium. • The margin of umbrella, in between notches, is provided with numerous, small, closely arranged hollow marginal tentacles. The margin of umbrella, bearing marginal lappets and marginal tentacles, is thin ridge-like called velarium or pseudo velum. A true velum like those of hydrozoan medusae is absent in Aurelia because it lacks muscles and nerve ring.

5. Histology of Aurelia Aurita • Ectoderm: • The ectoderm (epidermis) covers the bell all around, it has the columnar epitheliomuscular cells, sensory cells, nerve cells which produce mucus. • Endoderm: • The endoderm (gastro dermis) has columnar ciliated epithelial cells, they have no muscle processes; the endoderm lines the enteron except the gullet.

6. Life Cycle of Aurelia • Reproduction in Aurelia: • The sexes are lodged in distinct individu­als and. the four horseshoe-shaped gonads are either testes or ovaries. The spermatozoa or ova are shed in the stomach. The sperma­tozoa come to the exterior with water current and enter the stomach of a female individual with water current. Fertilization is internal.

7. LIFE CYCLE OF AURELIA

8. Development and Life History of Aurelia • i. The zygote divides regularly and a blastula is formed. • ii. By invagination of the blastula an oval, two-layered ciliated planula larva is formed, blastopore of which is not closed. • iii. After a brief period of free life, the larva settles down by the end opposite to the blastopore, loses its cilia and gradually trans­forms into a hydra tuba. • iv. A definite mouth is formed at the distal end. • v. On the opposite side of the mouth two tentacles are formed by out-pushing. Soon two others appear at right angles to the first pair; then four, and subsequently eight more tentacles appear. The larva is now provided with sixteen tentacles arranged in a circlet. • vi. By this time, the proximal end narrows down to a stalk-like structure the stolon, and the distal end becomes expanded. • vii. Inter-radial in position, the endoderm of the gastric cavity is folded into four lon­gitudinal ridges, the gastric ridges or taenioles.

9. viii. The mouth assumes a square shape and its sides are elevated to form a short manubrium. • ix. The ectoderm of the region between the mouth and the circlet of tentacles be­comes invaginated in four inter-radii to form four septal funnels or infundibula, which sink in the four gastric ridges. • x. The hydra-tuba feeds and produces new hydratubae by budding from its stolon throughout the summer. The buds may sepa­rate from the mother hydra-tuba. Budding ceases at the end of the summer. • xi. The hydra-tuba stage persists for a long period and undergoes strobilation or trans­verse fission in the next year. • xii. This stage of a scyphozoan polyp is known as scyphistoma larva, and it is about 1.25 cm in length. • xiii. Several transverse constrictions appear on the larva and, as the constrictions grow deeper, the larva appears like a pile of discs, one placed above the other. • xiv. The edge of each disc is provided with eight bifid arms bearing deep notches. As the constriction proceeds, the stomach becomes closed on the lower surface of each disc, while on the upper surface it remains open and its outer edges are transformed into a manubrium. • xv. Finally, the disc-like bodies separate form one another, turn upside down and are known as ephyra. Each ephyra carries with it a part of the stomach with the gastric ridges. • xvi. The mouth becomes elevated on the manubrium, tentaculocysts appear at the notches of the bifid arms, gastric filaments appear on the gastric ridges, soon followed by others and the stomach extends in the arms.

10. PHYLUM COELENTERATE - PHYSALIA

11. HABIT AND HABITAT • Physalia is a marine, colonial, floating, pegagic coelenterate. • Distribution : Found in the warm sea in the gulf stream from Florida or veneyard, USa GENERAL CHARACTER • 1) Commonly called as Portuguese man of war it is so named because of its sudden appearance and disapperance like portuguese ships during war. • 2) Most beautiful siphonopore havng irredescent peacock blue or organge colour • Size 10 to 30 cm long but tentacles measure several metres. • A body composed of upper large crested pneumatophore or float of lower various zooids

12. Pneumatophore contains gas galns which screte air composed off 7.5% to 13.5% oxygen 1.5% orgaon and 85% ot 91% introgen. • Gas fills the float to swim or float and when animal has to snik gas is forced out through the Pnecumatophore • Ventrally the float contains budding coenosare from which small dactylozooids large dactylozooids gastrozooids, gonozooids and gonodendra hanving down. • A Small dactylozooids gatstrozooids gonodendra, gonozooids gonopalpans gelatinous zooids, gonopalpans large fishing tentacle, batteries of nematocycts and small portion of gonodendra a part of gonodendra shows upper small male gonophores lower large rounded femals gonophores with eggs along with gonophores and several cylindrical gonopalpans