Sunflower sea star

The sunflower sea star is the largest sea star known to humans. It was given the name sunflower for its likeness to the sunflower. The sunflower sea star looks like a sunflower because it has many arms. It can be found in the Pacific Ocean.

Kingdom: Animalia

Phylum: Echinodermata

Class: Asteroidea

Order: Forcipulatida

Family: Asteriidae

Genus: Pycnopodia

Species: Helianthoides

As the largest sea star, the sunflower sea star may grow to a diameter of over 3 1/2 feet (one meter) and may have as many as 24 arms surrounding its central axis. A central axis is a central point from which things may extend. The body construction of having a central axis and arms extending in a circle around that axis is known as radial symmetry. All echinoderms, or spiny-skinned animals, are radially symmetrical. Like other sea stars, the sunflower sea star has the power to regenerate lost limbs. This means that if the sunflower sea star loses one of its arms it is able to grow a new arm.

On the bottom of the arms of this giant echinoderm are hundreds of rows of tiny, tube-like tentacles, or tube feet. These feet are used by the sunflower sea star in the process of moving along the seabed and in opening bivalve mollusks.

The sunflower sea star is typically found along the western coast of North America from Alaska south to California. Like other sea stars, the sunflower sea star moves along the ocean floor in search of food. Typically, the sunflower sea star is found in intertidal zones and deeper waters just offshore. It is often found in oyster and clam beds feeding on oysters and clams.

The sunflower sea star survives on a diet of bivalve, or two-shelled, mollusks. It is a carnivore, or meat eater. Although it will eat most bivalve mollusks, it is often found feeding on oysters and clams. The sunflower sea star may also sometimes feed on sea urchins, sponges, corals, worms, crustaceans, other sea stars, and small fish when bivalve mollusks are not available.

Like other sea star, the sunflower sea star has a special method for opening its prey. First, it wraps its body around the tightly-sealed shell of the mollusk. As it is doing this, it attaches its tube feet, like tiny suction cups, onto each of the shells of the mollusk and pulls the creature open. As it opens the mollusk, the sunflower sea star pushes its stomach out through its mouth and into the body of the mollusk. There it releases digestive fluids which begin to break down the body of the mollusk. As the mollusk's body becomes a soft, mushy soup, the sunflower sea star sucks the mixture into its stomach. It then releases the mollusk and returns to its normal shape.

The sunflower sea star typically mates during the spring in May and June. The process begins when male and female sunflower sea stars release their sperm and eggs into the water. The eggs are then fertilized in the water and begin developing into sunflower sea star larvae. This system of releasing eggs and sperm into the water for external fertilization is known as spawning. As a sunflower sea star larva, this creature floats through the surface levels of the water, feeding on tiny creatures. After two to 10 weeks, it develops stronger arms and settles to the ocean floor, where it continues to develop into an adult sunflower sea star. On the ocean floor, it grows a sea star bud and changes form. Eventually, the sunflower sea star larva becomes a miniature adult sunflower sea star and continues to grow to its full-grown adult size.

Other sea stars, otters, seagulls, and sea urchins may prey on the sunflower sea star. The life span of this giant sea star is between five and 7 1/2 years, although many live decades longer. The sunflower sea star is a critically endangered species.

Bibliography

“Sunflower Sea Star.” NOAA Fisheries, 11 Apr. 2023, www.fisheries.noaa.gov/species/sunflower-sea-star. Accessed 9 May 2024.

“Sunflower Star - Animals.” Monterey Bay Aquarium, www.montereybayaquarium.org/animals/animals-a-to-z/sunflower-star. Accessed 9 May 2024.