Decades of research add more than 1,000 marine invertebrate species to South Africa’s biodiversity list

When most people think of South Africa's marine life, they picture whales, great white sharks, or colourful reef fish. Yet these iconic animals represent only a small fraction of the country's extraordinary marine biodiversity. Hidden beneath the waves on the seabed, is a vast and largely unseen world of invertebrates such as sponges, corals, sea slugs, sea stars, crabs, worms, sea cucumbers and countless others that form the foundation of healthy marine ecosystems.

A new chapter published in Advances in Marine Biology brings together decades of taxonomic research to provide the most comprehensive update in more than a decade on South Africa’s marine benthic invertebrate biodiversity.

A major update to South Africa’s marine species inventory

The work builds on two foundational national assessments published in 1999 and 2010, providing the first comprehensive update in 16 years.

Since the previous assessment, researchers have added more than 1,000 marine benthic invertebrate species to South Africa’s known fauna. These discoveries span habitats from the intertidal zone to the deep sea and include species that are found nowhere else in the world.

With these additions, South Africa’s known marine biodiversity now almost certainly exceeds 14,000 species.

But the numbers tell only part of the story.

Behind every new species lies years of painstaking work: collecting specimens from remote coastlines and deep-sea expeditions, comparing microscopic anatomical features, examining historical museum collections, and generating DNA sequences to confirm whether an organism truly represents a species new to science.

A major outcome of the chapter is not simply an updated species count, but a new resource for the scientific community.

For the first time, each taxonomic group covered by the chapter is accompanied by a permanently citable, openly accessible species list, with its own Digital Object Identifier (DOI).

Making these lists openly available provides researchers, conservation practitioners, and policymakers with a reliable reference point for tracking future changes in South Africa’s marine biodiversity.

It also means that future discoveries can be added to an established and citable baseline.

Significant gaps remain

Despite encouraging progress, many marine invertebrate groups remain poorly understood. Active South African taxonomic specialists are lacking for several phyla, deep-sea habitats are under sampled, and molecular reference databases remain incomplete. South Africa almost certainly harbours many more undescribed species awaiting discovery.

Knowing what species exist is far more than an academic exercise. Accurate species inventories underpin marine conservation, environmental impact assessments, fisheries management, invasive species detection and climate change monitoring. They also form the foundation for biotechnology and marine natural products research, where novel compounds from marine invertebrates hold significant potential for drug discovery.

A roadmap for the future

The chapter sets clear priorities for South African marine biodiversity research including expanding taxonomic capacity, investing in museum collections, strengthening DNA reference libraries, increasing deep-sea exploration, and supporting long-term biodiversity monitoring. These recommendations come at a critical time as global efforts accelerate to document and conserve biodiversity under rapid environmental change.

South Africa now has its most comprehensive picture yet of its benthic marine invertebrate fauna, enriched, for the first time, with permanently citable, DOI-linked species lists freely available to researchers, managers, and policymakers worldwide. Despite decades of dedicated work, we have only begun to uncover the extraordinary diversity hidden beneath our seas.