Biology Key Terms: Invertebrates, Chordates, Symmetry, and More

Invertebrate

An animal that lacks a vertebral column or backbone.

Chordates

Animals belonging to the phylum Chordata, characterized at some stage of development by a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

Vertebrates

Animals that possess a backbone or spinal column, which is part of the endoskeleton.

Feedback Inhibition

A process in which the product or result of a process stops or limits the process itself, helping to maintain homeostasis.

Radial Symmetry

A body plan in which body parts are arranged around a central axis, such that any plane passing through the center divides the organism into mirror images.

Bilateral Symmetry

A body plan in which an organism can be divided into two identical left and right halves along a single plane.

Zygote

A diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

Coelom

A fluid-filled body cavity that is completely lined with mesoderm tissue, providing space for internal organs.

Cephalization

The evolutionary trend of concentrating nervous tissue and sensory organs at the anterior end of an organism, forming a head.

Cartilage

A strong, flexible connective tissue that provides structural support in various parts of the body, such as joints and the skeleton.

Tetrapods

Vertebrates that have four limbs or are descended from four-limbed ancestors.

Hominoids

A group of primates that includes humans, apes, and their extinct ancestors.

Opposable Thumb

A thumb that can be placed opposite the fingers of the same hand, allowing for grasping and the manipulation of objects.

Bipedal

The ability to walk or move on two legs as the primary form of locomotion.