How the Six-Rayed Sea Star Protects Her Babies From Danger

When it comes to raising and propagating young, different creatures have different approaches. Mammals typically have a small litter of offspring that they raise to varying degrees before setting them off on their own. Marine life, however, tends to take a ‘spray and pray’ approach, often releasing hundreds or even thousands of eggs at a time to maximize the chances of the species survival. In this YouTube video, viewers witness a starfish protecting a tiny group of eggs.

Starfish may seem slow, even immobile, but they are complex creatures capable of great feats, not least of which is raising their delicate young. Six-rayed sea stars go to great lengths to brood their future children and give them the best shot at life. Let’s learn more about these sea stars, their reproduction strategies, and impressive maternal instincts.

All About the Six-Rayed Sea Star

Six-ray sea stars (Leptasterias hexactis) are a type of starfish in the Asteriidae family. They have small, squat bodies with a diameter of about two inches and six arms. Their aboral, or upper, surface color ranges from grey to brown and green, with some specimens displaying a rusty red hue. These starfish are covered in short, mushroom-shaped spines. On their oral, or underside, they have tube feet with suckers running the length of their arms.

Six-rayed starfish, or sea stars, live exclusively in the intertidal zone of the northeast Pacific Ocean, where the surf meets the land. Along the west coast, from the San Juan Islands in the north to the Channel Islands in Southern California, six-rayed stars thrive. They prefer partially exposed intertidal areas that are pounded by the waves. When the tide goes out, six-rayed stars cling to the underside of boulders using their tube feet. They can also be hidden in seaweed.

Six-rayed stars may look pretty and relatively innocuous, but they are fearsome predators in the intertidal region. They are carnivores, capable of attacking and subduing large prey. Their diet includes snails, mussels, chitons, barnacles, sea cucumbers, and the carcasses of dead animals like birds. They also have competition for these food sources from larger, more colorful purple sea stars. This YouTube video shows a six-rayed star nurturing her babies as they grow. Let’s learn more about this fascinating process.

Reproduction

Between November and April in places like the Puget Sound in Washington State, male and female six-rayed stars come together for mating season. They are known to stack on top of each other. Males will release their sperm onto the female’s body, where she lays her eggs, to increase the chance of fertilization. The most fascinating thing about six-rayed star mating, however, is the female doesn’t let the eggs drift away like other starfish. Instead, she clings to them for dear life.

Precious Cargo

Once successful fertilization has occurred, the mother starfish goes into serious mode. She holds the fertilized eggs with her tube feet in a bundle that she keeps near her mouth. Other starfish and sea creatures lay thousands of eggs at a time, but six-rayed stars must be careful because they lay only between 50 and 1,500 eggs, depending on the size of the female.

To accommodate her babies, the mother six-rayed star will also arch her body up in a process called brooding. In the natural world, brooding typically refers to the process in which mother birds cease laying eggs and then sit on top of them to incubate them. Six-rayed stars are one of the few non-avian creatures to engage in this nurturing behavior.

Relatives of six-rayed stars, like other starfish and sea urchins, release sperm and eggs by the boatload into the water and let the currents do the rest of the work. Six-rayed stars are more meticulous. They are also willing to sacrifice their own comfort to ensure their babies reach maturity. As her brood grows, a female six-rayed star will gently clean her eggs and tend to their needs.

This nurturing process takes so much work that mother six-rayed stars don’t eat for three months straight. Plus, the egg bunch sits directly in front of her mouth. The baby starfish don’t have mouths, so they subsist on energy stored inside their own bodies. In this YouTube video, viewers get an up-close and personal look at this process.

Growing Pains

After about a month of growing, baby six-rayed stars reabsorb their arms and grow six new ones. After a few more weeks, the babies detach from their mother and venture out into the intertidal region on their own six feet. Measuring no more than a millimeter wide, the baby six-rayed stars resemble tiny snowflakes. Make no mistake, however, as they are already hungry for prey.

In this YouTube video, the baby six-rayed starfish find juvenile barnacles and snails and gobble them up. Thus, the life cycle of the six-rayed starfish begins again. It’s a fascinating process, filled with surprising acts of protection and nurturing.