Common brittle star
The common brittle star, a member of the phylum Echinodermata and class Ophiuroidea, is a slender and agile marine creature characterized by its easily breakable, star-shaped body. Typically found along the ocean floor of the British Isles, the eastern North Atlantic Ocean, the North Sea, and the Mediterranean Sea, this species features a small disk-like center about one inch wide, from which at least five long, flexible limbs extend. Each limb can reach up to four inches long and is equipped with thousands of hollow tube feet that produce mucus, aiding in the capture of small floating organisms, its primary food source.
Common brittle stars live in large groups known as brittle star beds and exhibit cryptic coloration for predator evasion. They possess a remarkable ability to regenerate lost limbs, a defensive adaptation against predators. Reproduction occurs in warmer waters when food is abundant; males and females release sperm and eggs into the water, leading to the development of larvae that float before settling to the seabed. Despite not having a formally evaluated conservation status, the common brittle star's population appears to be stable and healthy, with a lifespan of about ten years.
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Common brittle star
The common brittle star is a spiny-skinned creature. Brittle stars are a quicker, more slender version of sea stars. It was given the name brittle star for its rough, easily-breakable, star-shaped body.
Kingdom: Animalia
Phylum: Echinodermata
Class: Ophiuroidea
Order: Ophiurida
Family: Ophiothrichidae
Genus: Ophiothrix
Species: Fragilis
The common brittle star generally inhabits the ocean floor along the British Isles and other coastal borders including the eastern North Atlantic Ocean, the North Sea, and the Mediterranean Sea. Like starfish, the common brittle star glides along the seabed in search of food.
The common brittle star has a small disk-like body and at least five limbs. The body of the common brittle star is about one inch (two and a half centimeters) wide and looks like a tiny sand dollar. They have cryptic coloring, which helps them avoid predators. The limbs which extend from this disk may be up to four inches (ten centimeters) long each. These limbs are covered with thousands of tube feet. The tube feet are hollow and produce mucus which aids in the process of catching prey. The disk-shaped center of the common brittle star holds all of this creature's internal organs. The outer covering of this disk is hard and rough and often bears a star-like symbol similar to the markings on a sand dollar.
The common brittle star feeds on small, floating organisms. It picks up these organisms with sticky mucus. As the common brittle star sweeps its limbs through the water, tiny organisms stick to the mucus on each of its limbs. As prey gets trapped in the mucus, the common brittle star's tube feet roll around the prey and push it into the groove within each limb. This groove carries the prey to the mouth of the common brittle star. Large numbers of common brittle stars live together in what is known as brittle star beds. They cling to rocks and to one another as they sweep their limbs through the water catching food.
As its name suggests the common brittle star is very brittle. This means it breaks easily. When the common brittle star is attacked by a predator such as the seven-armed starfish, the common brittle star often loses a limb in the struggle. Fortunately, the common brittle star can regrow lost limbs. This ability is called regeneration.
Mating for the common brittle star takes place when the water is warm and food is plentiful. Each common brittle star releases either sperm or eggs into the water. The eggs are fertilized and begin to develop into tiny common brittle star larvae. The larval common brittle star spends the first few weeks of its life floating through the water's surface level and feeding on tiny plants and animals. During this time, the common brittle star goes through many stages. Eventually it settles to the seabed and matures into an adult common brittle star.
Scientists suspect that chemical signals cause both male and female common brittle stars to release their sexual cells. Oftentimes, large groups of common brittle stars release their eggs and sperm together. During this process many eggs are fertilized, however, many of the sex cells are washed away on the current.
The life span of the common brittle star is ten years. This species has not been evaluated for a conservation status, but due to their abundance, it can be assumed the common brittle star's population is healthy.
Bibliography
Boyd, Stephanie. “Brittle Stars.” Texas Saltwater Fishing Magazine, Apr. 2023, www.texassaltwaterfishingmagazine.com/fishing/brittle-stars. Accessed 18 Apr. 2024.
Holland, Patricia. “Ophiothrix Fragilis.” Animal Diversity Web, 2012, animaldiversity.org/accounts/Ophiothrix‗fragilis/. Accessed 18 Apr. 2024.
Jackson, Angus. “Common Brittlestar.” The Marine Life Information Network, 5 Aug. 2008, https://www.marlin.ac.uk/species/detail/1198. Accessed 18 Apr. 2024.