invertebrae

Invertebrates are animals that do not possess a vertebral column, more commonly known as a backbone or spinal column. This defining characteristic sets them apart from the subphylum Vertebrata, which includes mammals, birds, reptiles, amphibians, and fish. Despite lacking a backbone, invertebrates represent the vast majority of animal species on Earth, making up an estimated 95% of all known animal life. They exhibit an incredible diversity in form, function, and habitat, ranging from microscopic organisms to large marine creatures.

The phylum Arthropoda, which includes insects, arachnids, crustaceans, and myriapods, is the largest phylum within the invertebrate kingdom. Other major invertebrate phyla include Mollusca (snails, clams, squids), Annelida (segmented worms), Cnidaria (jellyfish, corals), Echinodermata (starfish, sea urchins), and Porifera (sponges). Invertebrates inhabit nearly every environment imaginable, from the deepest oceans to the highest mountains, and from arid deserts to lush rainforests. Their ecological roles are diverse and crucial, including pollination, decomposition, nutrient cycling, and serving as a food source for other animals. Their simple body plans, in many cases, have allowed for remarkable evolutionary success and adaptation.