Invertebrate

What is an Invertebrate?

An invertebrate is an animal that lacks a vertebral column or spine. In other words, invertebrates lack a backbone or a notochord. The term “invertebrate” encompasses a vast and diverse group of animals that comprise most of the animal kingdom. Invertebrates represent a wide range of forms, sizes, and habitats.

Characteristics of Invertebrates

Absence of Vertebral Column

The defining characteristic of invertebrates is the absence of a vertebral column or backbone. Instead, they may have other structural features, such as exoskeletons, hydrostatic skeletons, or no skeletal structure.

Diversity of Body Plans

Invertebrates exhibit a remarkable diversity of body plans, ranging from simple and symmetrical forms to complex and highly specialized structures. This diversity includes animals with bilateral symmetry, radial symmetry, and asymmetry.

Major Phyla of Invertebrates

Invertebrates are classified into numerous phyla, each representing distinct evolutionary lineages. Some major phyla of invertebrates include Arthropoda (insects, spiders, crustaceans), Mollusca (snails, clams, octopuses), Annelida (earthworms, leeches), Cnidaria (jellyfish, corals), and Echinodermata (starfish, sea urchins).

Exoskeletons and Endoskeletons

Some invertebrates, such as arthropods (insects, spiders, crustaceans), have exoskeletons made of chitin for support and protection. Others may have internal skeletons or no skeletal structure at all.

Lack of Internal Skeletal Support

Unlike vertebrates, invertebrates lack an internal skeletal support system. Instead, they often rely on external structures, fluid-filled cavities, or other mechanisms to maintain body shape and function.