Animal Kingdom

ClosePorifera (sponges) have a canal system with tiny pores called ostia and a larger osculum for water flow, which aids in feeding, respiration, and excretion.

CloseIn cnidarians (e.g., Hydra), the polyp is a sessile, cylindrical form adapted for a fixed existence, often with tentacles facing upward.

CloseEarthworms exhibit bilateral symmetry (body can be divided into two identical halves only by one plane through the median axis). Adult starfish have radial symmetry.

CloseA true coelom is a fluid-filled body cavity completely lined by mesoderm-derived peritoneum, found in annelids, arthropods, mollusks, and chordates.

CloseAll chordates possess a notochord (a flexible rod supporting the body) at some stage of their life cycle, along with a dorsal hollow nerve cord and pharyngeal slits.

CloseArthropods (e.g., insects, crustaceans, spiders) have jointed appendages and a tough exoskeleton made of chitin, which is molted periodically for growth.

CloseAmphibians (e.g., frogs, salamanders) have a three-chambered heart and moist, glandular skin without scales, which aids in cutaneous respiration.

CloseThe water vascular system is a unique hydraulic system of echinoderms (starfish, sea urchins) consisting of tube feet used for movement, adhesion, and feeding.

CloseTapeworms (Platyhelminthes) are triploblastic (three germ layers) and bilaterally symmetrical. Sponges are asymmetrical and diploblastic; cnidarians are radially symmetrical and diploblastic.

CloseMany marine mollusks and annelids have a free-swimming trochophore larva, which is ciliated and helps in dispersal.

CloseAscaris (roundworm) belongs to phylum Nematoda, not Annelida. Annelids are segmented worms (e.g., earthworm, Nereis, leech).

CloseThese three features (muscular foot for locomotion, visceral hump containing organs, and mantle that secretes the shell) are defining traits of mollusks (e.g., snail, oyster).

CloseCartilaginous fish (sharks, rays) have a skeleton of cartilage, 5-7 exposed gill slits, and a tail with unequal lobes (heterocercal).

CloseCtenophores are named for their eight external rows of ciliated comb plates, which beat in coordination for propulsion. They lack cnidoblasts but have colloblasts.

CloseEarthworms (Annelida) have a closed circulatory system where blood flows through vessels. Arthropods (cockroach, grasshopper) and most mollusks (snail) have an open circulatory system.

CloseIn binomial nomenclature, the first name is the genus (Canis), and the second name is the specific epithet (familiaris), which together denote the species.

CloseFlightless birds (ratites) like ostrich, emu, and kiwi have a flat sternum (without a keel) because they lack large flight muscles. Flying birds have a keeled sternum.

CloseCnidarians and ctenophores are diploblastic, meaning their body develops from two germ layers (ectoderm and endoderm) separated by a gelatinous mesoglea.

CloseAll echinoderms (starfish, sea urchins, sea cucumbers) are marine animals with endoskeleton of calcareous spines and tube feet for locomotion.

CloseThe tadpole is an aquatic larva with gills, a two-chambered heart (like fish), a tail for swimming, and is herbivorous. It undergoes metamorphosis to become an adult frog with lungs and a three-chambered heart.