Starfish are star-shaped marine invertebrates that are found in oceans all around the world, from the shallow coastal waters to some the deepest depths possible. Starfish are incredibly unique animals and most eat by turning their stomach inside out through their mouths to engulf their prey. There are around 2,000 species of starfish, including some that are extremely venomous. As well as venomous and non-venomous starfish, there is a vast array of sizes, and the biggest are much larger than you would ever expect. Here we’ll discover the largest starfish in the world ranked by diameter.
#10 Largest Starfish: Northern Pacific Sea Star
Also known as the Japanese common starfish, the Northern Pacific sea star is found in shallow waters around the coasts of Alaska, British Columbia, China, Japan, Korea, and Russia. Northern Pacific sea stars can reach a maximum diameter of 19.5 inches. They are also an invasive species in many other parts of the world and are on the list of the 100 most invasive species in the world. They have five arms which are covered in small spines. Northern pacific sea stars are a range of orange, yellow, and red colors on their dorsal sides, while they are completely yellow underneath. Northern Pacific sea stars mainly eat molluscs, but sometimes eats crabs, barnacles, and algae and their main predators are other starfish. Incredibly, if one of their arms is broken off then it can grow into an entirely new starfish.
#9 Largest Starfish: Stimpson’s Sun Star
Stimpson’s sun stars, also known as striped sun stars, are large starfish and have a diameter of around 19.5 inches. They are found on rocky surfaces in seas up to 2,000 feet deep around Japan and the west coast of America from California to Alaska. Stimpson’s sun stars have between eight and twelve arms and earn their name from their striking reddish-orange color. Their arms are long and slender and each one has two rows of tube feet on them. Stimpson’s sun stars feed on sea cucumbers, brachiopods, and sea squirts. Their main predator is the morning sun star.
#8 Largest Starfish: Red Cushion Sea Star
The red cushion sea star is also known as the West Indian sea star and has a diameter of around 20 inches. They live in the Caribbean Sea and the western Atlantic Ocean where they prefer shallow water of 120ft. In the winter they migrate offshore to avoid rough water. Red cushion sea stars are red, orange, or yellow. They have a broad disc and usually five arms, although they do sometimes have more. Red cushion sea stars are omnivores and feed on algae, sponges, and other small invertebrates.
#7 Largest Starfish: Mottled Star
Mottled stars get their name from their mottled appearance which is in shades of orange, brown, grey, or purple. They have five narrow arms which are often turned up at the tip and reach a maximum diameter of 20 inches. Mottled stars are found on the west coast of North America and in Bechevinskaya Bay where they are found on rocks at depths of around 230 feet. They are powerful starfish and can use their feet to pull apart the two halves of a mollusc shell in order to insert it’s stomach into the gap to feed on the contents. Morning sun stars, sunflower sea stars, and king crabs are their main predators.
#6 Largest Starfish: Antarctic Sun Starfish
The Antarctic sun starfish, or wolftrap starfish, is particularly distinctive as it has between 40 and 45 slender, flexible rays and can reach 23.5 inches in diameter. They are usually pale orange or pinkish-red colour and their rays are covered in overlapping scales. Antarctic sun starfish are found in cold water in the Antarctic to depths of around 1,800 feet. Antarctic sun starfish usually sit on rocks and extend their rays to search for food, seizing anything that passes by. However, small fish and invertebrates make up the majority of their diet.
#5 Largest Starfish: Giant Sea Star
The giant sea star lives up to its name as a giant with a whopping 24 inch diameter. Giant sea stars are found on the western coast of North America, usually on rocks and near the low tide mark. They generally have five wide arms and are either purple, yellow, orange, or brown. However, they are also covered in thick, blue spines that have white or purple tips on them, which is where they get their other name from – giant spined star. Giant sea stars eat a range of barnacles, gastropods, and limpets. Sea birds and sea otters are their only predators.
#4 Largest Starfish: Spiny Starfish
Spiny starfish are native to the eastern Atlantic ocean at depths down to 650 feet where they prefer rocks and muddy areas. They have five slim arms and a diameter of 27 inches. Each arm has three rows of white spines that have purple tips on them. They use their spines for protection and to help them gather food. Spiny starfish eat mainly molluscs and other small invertebrates.
#3 Largest Starfish: Pink Sea Star
As their name suggests, pink sea stars are generally pink in color. They have five thick arms and can reach 28 inches. Pink sea stars are native to the northeast Pacific ocean. They generally prefer the shallower water near the coast – usually no deeper than 360 feet. They live on the sea bed where they often dig in the muddy bottom for prey using their tube feet. Pink sea stars can dig up to 4 inches into the seabed for buried clams and then break them open. They are able hunters and often fight with the larger sunflower sea stars over food. Sheep crabs, sea otters, morning sun stars, and seagulls are the main predators of pink sea stars.
#2 Largest Starfish: Sunflower Sea Star
One of the biggest starfish is easily the sunflower sea star with an 39 inch diameter. Sunflower sea stars have between 16 and 24 arms and can be virtually any color. They are found in the northeast Pacific ocean and they feed on sea urchins, snails, and clams. The king crab is their main predator and incredibly sunflower sea stars can shed an arm if they need to escape from predators quickly. Luckily, their arms grow back within a few weeks! Sadly, although they were once found in abundance, the population of sunflower sea stars has declined rapidly and they are now critically endangered.
#1 Largest Starfish: Midgardia Xandaros
The largest starfish in the world is Midgardia xandaros with a massive 53 inch diameter. These little-known starfish are particularly unusual as they have a very small central disc that is only 1 inch across but extremely long arms. Midgardia xandaros have twelve arms that are covered in spines. They are found in deep water in the Gulf of Mexico – around 2,000 feet deep. As they live so deep down very little is known about them, nor have they ever been observed in their natural habitat.