Invertebrate Zoology

Arachnids are eight-legged arthropods including spiders, scorpions, ticks, and mites. Cockroaches are insects (six legs), making them the correct answer for 'not an arachnid'.

Cockroaches can survive for approximately 9 days without their heads due to their decentralized nervous system. They breathe through spiracles (small openings) on their body segments, and their vital functions are distributed throughout their body. They eventually die from dehydration or inability to eat, not from brain loss.

Butterflies have taste receptors (chemoreceptors) located on their feet, which allows them to taste food simply by landing on it. This helps them identify potential food sources and host plants for their larvae.

A group of cockroaches is collectively called an 'intrusion,' which appropriately describes their typically unwanted presence in human spaces. The other terms are used for different contexts: a college refers to an educational institution or group of specialists, delegation is a group of representatives, and excursion refers to a short journey.

Cockroaches have hemolymph (insect 'blood') that is colorless or whitish, not red like vertebrate blood. This is because they don't use hemoglobin for oxygen transport.

The largest cockroach species reach lengths greater than 3.81 inches. The Central American giant cockroach (Blaberus giganteus) and other Megaloblatta species can exceed 4 inches (10+ cm), making the stated record incorrect.

Insects rely on a trade-off between sensory organs - those with well-developed compound eyes typically have shorter antennae, while those with poor vision develop longer antennae for enhanced tactile and chemical sensing, making option A correct.

Spiders is the correct answer. Arachnophobia comes from the Greek words 'arachne' (spider) and 'phobos' (fear). It is the specific phobia of spiders and other arachnids. Grasshoppers, lizards, and cockroaches are the subjects of different phobias (entomophobia, herpetophobia, and katsaridaphobia respectively).

Earthworms have no eyes - they detect light through specialized light-sensitive cells (photoreceptors) located in their skin. They sense light and dark but cannot form images.