Starfish Habitat: Where Sea Stars Actually Live, Animal Sake

In this article, we shed light on one of the little-known attributes of the life of starfish, their natural habitat, and the adaptations that help them survive in it.

Starfish or Sea Stars?

Some scientists argue that the term starfish doesn't make sense, because these animals are not related to fish at all. They suggest using sea star instead. Even so, both terms are in use today.

With somewhere around 1,500 species found in different oceans of the world, there is no questioning the diversity in the starfish family, the Asteroidea class of kingdom Animalia. Sadly, most of what we know about these animals comes from specimens washed ashore. That explains why so many people are unaware of some of the most interesting facts about them.

Starfish Distribution and Habitat

Geographical Range

Starfish are found in all the oceans of the world, which isn't really surprising given that there are more than 1,500 recognized species. Besides the Pacific Ocean, the Indian Ocean, and the Atlantic Ocean, starfish are also found in the Arctic Ocean and in the region where the Southern Ocean and the Antarctic Ocean meet. They only live in oceans because their delicate internal electrolyte balance is only in equilibrium with saltwater.

Several starfish clustered together on a rocky beach at low tide — Sea stars gathered on a rocky beach, these are the species most commonly seen, as they live near the shoreline.

Where Are the Most Starfish?

The largest concentration of sea stars is found in the tropical Indo-Pacific region. However, the tropical-temperate waters around Australia and the cold-temperate waters of the Northern Pacific Ocean also have plenty of starfish. Interestingly, experts believe that scores of starfish species living in the dark depths of the oceans are yet to be discovered.

Natural Habitat

The natural habitat of starfish spans from the intertidal zone (the seashore that is exposed to air at low tide and goes underwater at high tide) all the way down to the abyssal zone, which has a depth of roughly 4,000-6,000 meters. As mentioned, most of what we know about starfish comes from species washed ashore. These are the ones that live in the intertidal zone.

An orange sea star clinging to a rocky Pacific coast tidal pool, barnacles and mussels surrounding it — The intertidal zone (exposed rocks at low tide) is the most familiar starfish habitat. These tough animals can survive being out of water for short periods.

Some starfish species live on the deep sea floor, where very little light reaches. Because they live on the seabed, these species are grouped as benthos, organisms that live on, in, or near the seabed, also called the benthic zone. Since starfish have their mouth on the underside of their body, living on the seafloor makes it easy for them to feed on the tiny marine animals found there.

A pale brittle star on the dark deep-sea floor with long spindly arms outstretched — Deep-sea brittle stars belong to the same class as starfish. They thrive in total darkness on the abyssal floor, far beyond where divers can reach.

Take the Starfish Habitat Quiz!

5 quick questions. How much do you know about where sea stars live?

Starfish are sometimes found in small holes in rocks, gaps left by other marine animals they share their habitat with. They also prefer coral reefs, because corals are an important food source for them. In temperate and polar coastal oceans, starfish are found in kelp forests and kelp beds. Although they can live on many different seafloor types, the highest concentrations are found where the ocean floor is covered by a layer of algae.

The wide spread of sea stars' habitat comes down to their highly adaptable nature. They get used to different conditions with surprising ease. For example, the common starfish (Asterias rubens), found in the north-east Atlantic Ocean and the Indian Ocean, is also known to survive in estuarine water, the brackish mix where rivers meet the sea.

Threats to Starfish Habitat

Even though most starfish species are not yet threatened, experts believe they will eventually fall victim to pollution in their natural habitat. The main problem is their inability to filter contaminants dumped into the sea. As a result, they end up ingesting those pollutants and become vulnerable to life-threatening conditions. At the rate we are turning our oceans into dumping grounds, it won't be long before we see a clear decline in their numbers.

Term	Meaning
Intertidal zone	The strip of shoreline that is underwater at high tide and exposed to air at low tide. Many starfish species live here.
Abyssal zone	The deep ocean floor, typically 4,000-6,000 meters below the surface. Virtually no light reaches this zone.
Benthos / benthic zone	Organisms that live on, in, or near the seabed are called benthos. Deep-sea starfish are benthic animals.
Estuarine water	Brackish (partly salty) water where a river meets the sea. A few starfish species, like Asterias rubens, can tolerate it.
Electrolyte balance	The careful balance of salts and minerals inside an animal's body. Starfish need this to match saltwater, freshwater disrupts it fatally.
Indo-Pacific region	The tropical waters of the Indian Ocean and the western and central Pacific Ocean, the area with the greatest diversity of sea star species.

Here's All About the Habitat of Starfish

Starfish or Sea Stars?