GENERAL HISTOLOGY

Detailed explanation-1: -Today, spines or quills are found in four major groups of living mammals: hedgehogs (Erinaceomorpha : Erinaceidae, Erinaceinae), tenrecs (Afrosoricida: Tenrecidae, Tenrecinae), echidnas (Monotremata: Tachyglossidae), and rodents (Rodentia).

Detailed explanation-2: -echinoderm. Echinoderm, any of a variety of invertebrate marine animals belonging to the phylum Echinodermata, characterized by a hard, spiny covering or skin.

Detailed explanation-3: -Researchers estimate the porcupine has more than 30, 000 of these quills with as many as 100 to 140 growing from each square inch of skin. Only the nose, legs, and underside are unprotected. The rest of the body, from eyebrow to tail tip, is covered with prickly spines.

Detailed explanation-4: -The porcupine is the prickliest of rodents, though its Latin name means “quill pig.” There are more than two dozen porcupine species, and all boast a coat of needle-like quills to give predators a sharp reminder that this animal is no easy meal.

Detailed explanation-5: -Both porcupines and puffer fishes use this way of protection.