Animal Classification Overview

Three types of body cavities: schizocoelom, enterocoelom, and haemocoelom.

Internal skeleton; hard structure supporting and protecting an animal's body.

External skeleton; hard structure providing protection and support on the outside.

Solid, unsegmented rod supporting the dorsal (back) side of a chordate.

Animals without a notochord.

Determinate cleavage; embryo development where destruction of cells stops further development.

Non-determinate cleavage; embryo development where cells can form different structures.

Animal development involving a larval stage; young animal does not resemble the adult.

Sponges; multicellular animals with a cellular level of organization, found in aquatic environments, mostly marine.

Animals with tissue-level organization, radial symmetry, and unique stinging cells (cnidocytes), mostly aquatic.

Multicellular, with a cellular level of organization. Different layers, such as Pinacoderm, Choanoderm and Mesenchyme, make up the body wall.

Tissue-level, with outer epidermis and inner gastrodermis; a non-cellular mesoglea between the layers.

A system of canals within the sponge body that facilitates food and oxygen intake, and waste removal.

Body parts arranged around a central axis, like spokes on a wheel.

Animals with two germ layers (outer and inner) during development.

Comb jellies or sea walnuts; a distinct phylum with radial symmetry and a unique group of cilia for movement.

The body of Platyhelminthes (flatworms) is acoelomate, meaning the space between the body wall is filled with parenchyma. This fluid-filled parenchyma maintains body shape and acts as a hydroskeleton. The body wall contains mesodermal muscles (longitudinal, circular, oblique). They also have suckers for attachment to hosts.

Platyhelminthes are acoelomate, meaning they do not have a coelom (body cavity).

Platyhelminthes have an incomplete digestive system (no anus). The mouth leads to a pharynx, esophagus, intestine (which may branch into diverticula), but no separate anus.

They use flame cells (protonephridia) with cilia to filter waste and regulate water balance, also called solenocytes.

Platyhelminthes have a primitive ladder-like nervous system. It includes a brain around the pharynx, and longitudinal nerves connected by transverse nerves for signaling.

Platyhelminthes are hermaphroditic (having both male and female reproductive organs). Their life cycle is often digenetic (requiring two hosts).

A digestive system that lacks a separate opening for waste removal (anus). Materials enter and leave through the same opening.

Life cycles that have two hosts involved, such as flukes.

An independent phylum, previously considered a subphylum of Chordata, characterized by worm-like bodies with a proboscis, collar, and trunk.

A hollow outgrowth in the mouth region of some Hemichordata, resembling a notochord.

Hemichordata possess a structure resembling a notochord (buccal diverticulum), but true notochord is absent.

A subphylum of Chordata, characterized by tunicate-like organisms with notochord present only in larval stage.

The animal phylum including animals with a notochord, dorsal hollow nerve cord, pharyngeal gill slits, and a post-anal tail at some point in their development.

Hemichordates have a body plan with two symmetrical halves.

A leathery material forming a protective outer covering in urochordates.

Hemichordates have distinct male and female individuals.

Amphibian skin has mucus glands, keeping it moist for gas exchange.

Reptiles have a dry, rough, scaly or scutes-covered skin.

Reptiles are divided into two subclasses: Anapsida and Diapsida, based on skull openings.

Birds have a streamlined, spindle-shaped body, ideal for flight.

Bird forelimbs are modified into wings, crucial for flight.

Bird's gizzard helps in grinding food, which is essential for digestion and nutrient absorption.

Amphibians have a heart with three chambers, aiding in blood circulation.

Bird beaks are adapted for various diets, such as crushing, tearing, and nectar-sipping.

Birds use lungs in conjunction with air sacs, enabling unidirectional airflow for efficient gas exchange.

Mammals have a coelom divided into three distinct cavities: pericardial, pleural, and abdominal.

Mammalian bodies are typically divided into head, neck, trunk, and tail, with limbs for various actions (walking, running, flying, swimming).

Mammals have exoskeletons composed of components like nails, hair, scales, claws, hooves, and horns.

Mammalian hearts have four chambers, signifying warm-bloodedness.

Birds excrete uric acid (uricotelic) and lack a urinary bladder.

Subclass of mammals that lay eggs (oviparous).

Subclass of mammals that give birth to live young (viviparous). Divided into Metatheria and Eutheria.