Blue Tube Sponge, Haliclona (Soestella) caerulea

Blue Tube Sponge, Haliclona (Soestella) caerulea. Underwater photographs taken in Bahía La Ventana, El Sargento, Baja California Sur, April 2022. Photograph courtesy of Aaron Woodrow, Juneau, Alaska.

Phylogeny: The Blue Tube Sponge, Haliclona (Soestella) caerulea (Hechtel, 1965), is a member of the Chalinidae Family of Dermosponges. The Chalinidae Family has four genera and the Haliclona Genus has eight sub-Genus and the Soestella sub-Genus has twenty-seven species. The genus name Haliclona comes from the Greek words hali, meaning “sea” and “klon” meaning “branch”. The species name caeurulea comes from the Latin word for blue, like the sky or ocean. They are also known as the Blue Caribbean Sponge and in Mexico under the more generic name Esponja Marina.

Morphology: Blue Tube Sponges have radial symmetry form an encrusting mass characterized by cylindrical to volcano-shaped projections ranging between 2.0 cm (0.8 inches) and 15 cm (5.9 inches) in height and a maximum of 30 cm (12 inches) in diameter. The oscula cover the sponges surface at the high end and are circular or oval and between 1.5 mm and 5.0 mm in diameter serving as water outlets. The outside is covered with flattened pinacocyte cells. The inner part is formed by choanocyte cells equipped with a flagellum. These cells ingest food particles and also maintain the water flow through the body. Mesohyl, a gelationous substance is found between these two layers. Sclerocyte cells are responsible for secreting a kind of skeleton for supporting the sponge’s body, formed of spongin fibers. The Blue Tube Sponge is a striking electric blue or blue green with an occasional individual being beige or white. Their internal tissue is a contrasting dirty yellow. Their exterior consists of flattened cells called pinacocytes. Their interior is comprised of flagellated cells called choanocytes, which firn a complex system of canals the facilitate water flow and nutrient uptake. Its structural skeleton is formed by a framework of spongin fibers and curved, needle-like spicules (bent oxeas and C-shaped sigmas). Their surface is slightly textures resembling fine sandpaper to the touch. The body tissue is soft and easily torn. The Blue Tube Sponge is a straight forward identification.

Habitat and Distribution: The Blue Tube Sponge is an encrusting tubular sponge that is generally found anchored on rocky surfaces and coral reefs and growing in beds of the seagrass Thalassia, at depths up to 6 m (20 feet). They are not mobile and are restricted to the fouling communities, dredged channels and artificial lagoons. The Blue Tube Sponge are found in the western tropical Atlantic including Mexican waters of the Caribbean and the Gulf of Mexico in the Atlantic and along the west coast of the mainland in the Pacific Ocean. They have been relocated by biofouling on the hulls of ships.

Diet:  The Blue Tube Sponge differs from almost all other sponge species is dependent on photosynthetic interactions to produce its nutritional requirements. They are also a filter feeder, primarily consuming plankton and organic detritus from the water column through its oscula.

Predation:  The Blue Tube Sponge rely on its bioactive compounds to deter herbivorous fish and other potential grazers.

Reproduction:  The Blue Tube Sponge sexes are similar in appearance. It reproduces by both asexually via fragmentation or sexually being hermaphroditic. Sexual reproduction occurs by capturing sperm released into the water by adjacent individuals and transporting it to the eggs which are found in deep water.

Ecosystem Interactions:  Blue Tube Sponges contribute to the ecosy=o the ecosytem by filtering the water in a localized area and moving organic matter to higher trophic levels. They host various microorganisms and algae feeding on their wast materials contributing to its nutrient acquisition and overall health. They have symbiotic relationship with the Pink Segmented Algae, Jania adhaerens.

Human Interactions:  Blue Tube Sponge have no direct impact on human activities. They are utilized by the aquarium trade due to their brilliant color but are difficult to establish and difficult to maintain. They are often confused with and substituted by the Texotli Blue Sponge, Aphimedon texotli. A new lectin was isolated from the Blue Tube Sponge in 2013, that has been shown to involved in the process of cellular aggregation, symbiosis, and defense and growth regulation. From a conservation perspective they have not been formally evaluated.

Synonyms:  Haliclona caerulea and Sigmadocia caerulea.