Marine vertebrates encompass an incredible variety of animals, from tiny reef fish to ocean giants like the blue whale. Their common trait: a backbone that supports their body and protects the central nervous system.

These species have adapted to environments ranging from shallow coastal waters to the abyssal depths where sunlight never penetrates. Their anatomy, physiology and behavior reflect millions of years of evolution in aquatic environments.

Several major groups make up marine vertebrates: cartilaginous fish (sharks and rays), bony fish, marine mammals (dolphins, seals, sea lions, whales), as well as certain sea turtles and sea snakes.

Indeed, marine vertebrates are represented by four major classes, namely:

Each group displays remarkable adaptations: efficient gills to extract dissolved oxygen, fins and streamlined bodies to reduce water resistance, or lungs and the ability to dive for long periods for air-breathing species. This diversity allows them to occupy a wide range of ecological niches, from fast-moving hunters to peaceful filter feeders.

These vertebrates play an essential role in maintaining the balance of marine ecosystems. Predators regulate prey populations, herbivores help preserve the health of seagrass beds and some species even contribute to nutrient cycling: by feeding in deep waters and releasing waste near the surface, they transport key nutrients (nitrogen, phosphorus, iron) to sunlit zones where phytoplankton, at the base of the marine food web, can thrive.

However, many species are now threatened by overfishing, accidental bycatch in fishing gear, pollution and climate change. Studying and understanding them is crucial to protecting not only these species, but also the overall health of the oceans on which all life depends.