Invertebrate Zoology

Gray and Lissman conducted detailed studies on earthworm locomotion, describing how earthworms move through coordinated contraction and relaxation of muscles. This is a factual recall question about the history of zoological research.

Thesocytes are specialized cells in sponges that store food reserves, particularly nutrients and lipids. Archaeocytes are totipotent cells, scleroblasts produce spicules, and pinocytes are related to pinacoderm (covering layer). Option A appears to have a typo.

Amphids are paired chemosensory organs located in the lips of nematodes like Ascaris. They function as the primary olfactory and chemoreceptive structures, detecting chemical cues in the environment. They do not secrete saliva, act as adhesive organs, or produce proteolytic enzymes.

A maggot is the larval stage of a fly, specifically the housefly (Musca domestica) and related species. Houseflies lay eggs in decaying organic matter; the hatching larvae (maggots) feed before pupating into adult flies. Mosquitoes have aquatic 'wriggler' larvae, and frogs/fleas have completely different life cycles.

Choanocytes (or collar cells) are the feeding cells in sponges. Each choanocyte has a flagellum surrounded by a microvillar collar that creates water currents and traps food particles (bacteria, organic debris) which are then ingested by phagocytosis. Porocytes are pore cells, pinacocytes are covering cells, and trophocytes are nutritive cells in other animals.

Insects, including cockroaches, have an open circulatory system where hemolymph (insect blood) flows freely through body cavities (hemocoels) rather than being confined to blood vessels. Closed circulatory systems are found in vertebrates like humans and earthworms.

Halteres are club-shaped structures formed from the modified hind wings of flies (order Diptera, meaning 'two wings'). They function as gyroscopic sensory organs that help flies maintain balance during flight. The other orders listed (Lepidoptera - butterflies/moths, Orthoptera - grasshoppers/crickets, Hemiptera - true bugs) all have four functional wings and do not have halteres.

The tube-within-a-tube body plan refers to organisms with a complete digestive tract having both mouth and anus. Ascaris (a nematode) exhibits this body plan, unlike hydra and planaria which have a single opening (sac-like body plan).

Colleterial glands in female cockroaches secrete proteins that form the ootheca - the protective egg case. The ootheca hardens to protect the developing eggs and is deposited in sheltered locations.

Neuromasts are the specialized sensory cells found in the pits and canals of the lateral line system in fishes. They detect water movement and vibrations, helping fish navigate, avoid obstacles, and detect prey.

In insects, the alary muscles are wing-like muscles associated with the heart that help expand the heart chamber during diastole. These muscles are crucial for facilitating hemolymph flow through the dorsal vessel and are unique to the insect circulatory system.

In arachnids like scorpions, the prosoma (also called cephalothorax) is the anterior body tagma that results from the fusion of the head and thorax segments. The abdomen remains a separate posterior tagma (opisthosoma).

Mandibles of a cockroach help in mastication.

The heart may be suspended by alary muscles, contraction of which expands the heart and increases blood flow into it.