Spirobranchus
Spirobranchus is a genus of marine polychaete worms belonging to the family Serpulidae. Commonly known as Christmas tree worms or spiral tube worms, they are characterized by their distinctive crown of feathery tentacles, which are used for filter feeding. These worms are found in tropical and subtropical waters worldwide, inhabiting a wide range of coral reef environments.
Characteristics
Spirobranchus species are sedentary filter feeders, meaning they live in one place and feed by filtering water for food particles. They construct calcareous tubes that they live in, which are often brightly colored and intricately patterned. Their most striking feature is their crown of tentacles, known as radioles, which are arranged in a spiral pattern and resemble a Christmas tree. The radioles are covered in cilia, which create currents to draw water and food particles towards the worm's mouth.
The tube of a Spirobranchus worm is composed of calcium carbonate and is secreted by a gland near the worm's head. This tube is attached to a hard surface, such as a coral reef or rock, and serves as a protective shelter for the worm. When threatened, the worm retracts its radioles and hides inside its tube.
Spirobranchus species exhibit sexual dimorphism, meaning males and females differ in appearance. Females typically have longer radioles than males, and their tubes are often larger and more elaborate. Spirobranchus worms reproduce sexually, releasing sperm and eggs into the water column where fertilization occurs. The larvae are planktonic, meaning they drift with the ocean currents until they settle on a suitable substrate and begin to build their tubes.
Environment
Spirobranchus worms are found in tropical and subtropical waters worldwide, primarily in coral reef environments. They prefer areas with strong currents and clear water, as this provides them with a constant supply of food particles. These worms can be found on a variety of substrates, including live corals, dead coral skeletons, rocks, and even shells. Their brightly colored tubes often stand out against the backdrop of a coral reef, making them an easily recognizable and popular feature of these ecosystems.
Species
There are many recognized species of Spirobranchus, with some of the most common and well-studied including:
- Spirobranchus giganteus
- Spirobranchus kraussii
- Spirobranchus lamarckii
- Spirobranchus polytrema
These species can be distinguished from one another by their tube morphology, radiole color and pattern, and geographical distribution. Scientists continue to discover new Spirobranchus species, with the exact number of species in the genus still under debate.