Phyla and Classes of the Animal Kingdom

Chordata

A phylum that includes animals with a spine and a dorsal hollow nerve cord as its embryo.

Mammalia

A class within the phylum Chordata characterized by the presence of mammary glands, hair or fur, and the ability to maintain a constant body temperature.

Reptilia

A class within the phylum Chordata that includes reptiles characterized by their scaly skin and typically laying eggs on land.

Amphibia

A class within the phylum Chordata known for their dual life stages: an aquatic larval stage and a terrestrial adult stage.

Aves

A class within the phylum Chordata characterized by feathers, beaks, and the ability to lay hard-shelled eggs.

Chondrichthyes

A class within the phylum Chordata that includes cartilaginous fish such as sharks and rays.

Osteichthyes

A class within the phylum Chordata that comprises bony fish, generally with skeletons made of bone.

Porifera

A phylum of simple, porous animals known as sponges, characterized by their lack of true tissues and organs.

Cnidaria

A phylum that includes jellyfish, corals, and sea anemones, known for their radial symmetry and stinging cells.

Platyhelminthes

A phylum of animals characterized by flat bodies and the ability to regenerate lost body parts.

Annelida

A phylum consisting of animals with segmented bodies capable of regeneration without a backbone.

Mollusca

The second largest animal phylum with over 100,000 species, many of which live in aquatic environments.

Arthropoda

A phylum made up of 23 classes containing over 1.3 million species with segmented bodies and exoskeletons.

Echinodermata

A phylum characterized by radial symmetry and a tough outer skin, including species such as sea stars and sea urchins.

Polychaeta

A class of Annelida characterized by brightly colored, segmented bodies.

Oligochaeta

A class of Annelida that includes earthworms, characterized by small, tube-like bodies with bristles.

Hirudinea

A class of Annelida that contains leeches, which have two suckers and feed on blood.

Gastropoda

A class of Mollusca that includes snails and slugs, characterized by a single shell.

Cephalopoda

A class of Mollusca that includes octopuses and squids, characterized by arms, tentacles, and an ink sac.

Bivalvia

A class of Mollusca with compressed bodies without heads, protected by a hard exoskeleton.

Insecta

A class of Arthropoda that includes insects with three-part bodies and a pair of antennae.

Arachnida

A class of Arthropoda that includes spiders and ticks, characterized by eight legs and no antennae.

Crustacea

A class of Arthropoda with hard exoskeletons, segmented bodies, and gills for respiration.

Chilopoda

A class of arthropods known as centipedes, characterized by long bodies with many legs.

Diplopoda

A class of arthropods known as millipedes, characterized by two legs per segment and slow movement.

Echinoidea

A class of Echinodermata characterized by radial symmetry and spiny skin, such as sea urchins.

Asteroidea

A class of Echinodermata characterized by the presence of arms and a water vascular system, including sea stars.

Holothuroidea

A class of Echinodermata that includes sea cucumbers, characterized by tentacles around the mouth.