Invertebrate Zoology

In Pheretima, a cocoon contains many fertilised eggs but only one embryo completes development, while other ova serve as nurse cells. The development is direct without a free larval stage. After the development of 2-3 weeks, the young worm crawls out of the cocoon. So, the correct answer is option A.

There are two pairs of testes, which are situated in the 10$^{th}$ and 11$^{th}$ segments on each side of the alimentary canal. The germinal epithelium of the testis gives rise to the sperm cells by spermatogenesis. So, the correct answer is option B.

Earthworms are hermaphrodites; that is, they have both male and female sexual organs.  The two or four pairs of seminal vesicles produce, store and release the sperm via the male pores. Ovaries and oviducts are in segment 13 release eggs. Ovarian funnels are present beneath the ovaries which continue into the oviduct, join together.

The spermathacae are also called as receptaculum seminis. species of earthworms have four pairs of spermathecae one pair each in the 6th, 7th, 8th, and 9th segments. The spermathecae receive and store the spermatozoa of another earthworm during copulation. They are lined with epithelium and are variable in shape: some are thin, heavily coiled tubes.

• Vermi-processing toilets is a design of a toilet in which humans excreta is treated by earthworms and redworms.
• In this process, human excreta is completely converted to cake like structures called vermi cakes by earthworms. Vermi cakes are used mostly in the soil as manure and fertilizers.
•  Hence The worm used in the vermi-processing toilet is Redworm.
• So, the correct answer is 'Redworm'.

The cerebellum is made up of two lateral lobe and a large vermis lobe which is divided into nine segments. It is associated with the fastigial nucleus. It is concerned with the regulation of the regulation of the muscle tone for posture and locomotion. 

Among other visceral organs larva contains well- developed paired glands called silk glands. Silk is the secretion of salivary gland.

Metamorphosis is the process of development of organisms after hatching or birth. Insects that go through three stages of change in their life cycle have an incomplete metamorphosis. The first stage is the egg. During this time, the insect will hatch into a form, called a nymph. The nymph is basically a small version of the adult insect. Once a nymph outgrows its exoskeleton it will go through a process called moulting which is to leave the old skin or exoskeleton behind. The new skin will harden and become the new exoskeleton. This will happen many times until the insect finally becomes an adult. So, the correct answer is option B.

• Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa.
•  Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed.
• The remnants of the old, empty exoskeleton are called exuviae. 
• In arthropods, such as insects, arachnids and crustaceans, Moulting is the shedding of the exoskeleton (which is often called its shell), typically to let the organism grow. Hence, Shedding of the exoskeleton to replace it due to growth in the body is called ecdysis and moulting. 

Glands of swammerdam are soft chalky masses of calcareous bodies found in the dorsal root ganglion of spinal nerve in frog. These form reserve supplies of calcium.

Hydra vulgaris - is freshwater hydra, Hydra gangetic - Fresh water hydra, Obeila - sea water, Physalia - sea water. 

Acclimatisation is the process by which an individual organism adjusts to a change in its environment, allowing it to maintain performance across a range of environmental conditions.