Invertebrate Zoology

Slugs have four tentacles that serve sensory functions, with the lower pair primarily used for smelling and tasting, and the upper pair containing eyes but also having olfactory receptors. In trivia, these four sensory tentacles are commonly referred to as having "four noses."

Both amphibians (like frogs) and insects (like butterflies) begin their life cycles as eggs laid by the female parent. The larva and pupa stages occur later in development after the egg hatches.

The pupa stage is the inactive transition stage where the larva (caterpillar) develops inside a protective casing (chrysalis or cocoon) to become an adult. The egg is the starting stage, and the larva is the active feeding stage before pupation.

Metamorphosis is the biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure. While they do undergo changes, metamorphosis is the precise scientific term for this transformation.

Whether an animal undergoes complete or incomplete metamorphosis, the life cycle always begins with an egg. The larva and pupa are subsequent developmental stages that occur after hatching.

In the life cycle of a butterfly or moth, the larval stage is commonly referred to as a caterpillar. The pupa is the next stage (often inside a cocoon or chrysalis), and the butterfly is the final adult stage.

The egg apparatus is composed of one egg cell and two synergids, and the synergids possess the filiform apparatus.

Metamorphosis is the process of transformation from an immature form to an adult form in two or more distinct stages, common in insects like butterflies.

An exoskeleton is a hard external covering that provides support and protection for the bodies of many insects and other arthropods.

The life cycle of a butterfly begins with the egg stage, which is laid by the adult butterfly on a host plant.

The larva stage is an early, active, and often worm-like phase in the life cycle of many insects. It occurs after the egg hatches and before the insect enters the pupa stage.

Termites rely on symbiotic flagellates in their gut to break down the cellulose found in wood. Without these microorganisms, termites would be unable to digest their primary food source.

The silk worm spins a cocoon around itself during the pupa stage of its life cycle. This is the stage where the silk is harvested.

The silk fiber is produced by the silk worm as a liquid secretion from its glands, which hardens into a cocoon. The silk is harvested from this cocoon.

Nephron is the principal functional unit of the kidney of vertebrates. Its number reaches to one million in each kidney. Filtration of blood occurs in Malpighian body, later is composed of a tuft of capillaries called the glomerulus together with the cupped end of the renal tubules,
known as Bowman's capsule.