Species Description: The fire sponge, Tedania ignis, is one of several sponges commonly found in western Atlantic and Caribbean coastal waters, named for the burning sensation and rash it produces when touched (eg. Kaplan 1988). The fragile tissue of T. ignis forms large masses, bright red or orange in color externally and lighter inside (Voss 1980). Water exits the sponge through 1 cm wide openings called oscula. Each osculum is located at the top of cones, areas of the sponge raised approximately 1 cm from the surrounding tissue.
Potentially Misidentified Species: Approximately 5,000 species of sponges have been described, 90% of which are placed with T. ignis in the class Demospongiae (Ruppert & Barnes 1994). Several species of demosponges are found in various habitats within the IRL, many in association with the fire sponge. However, the conspicuous T. ignis can be easily identified, and further microscopic analysis of the shape of the internal skeletal structures, called spicules, can be used to distinguish this sponge from many other species.
Regional Occurrence & Habitat Preference: The range of T. ignis extends from Florida to Brazil, Bermuda and the Gulf of Mexico (Kaplan 1988, Wulff 2006). Masses of the sponge can be found on rocks, dead coral, in seagrass beds and on the prop roots of the red mangrove, Rhizophora mangle (Kaplan 1988).
IRL Distribution: The fire sponge can be found in several areas of the IRL, including: mangroves, seagrass beds and rock shorelines. Large populations of T. ignis have been collected from sponge communities growing on jetty rocks at the Fort Pierce Inlet in St. Lucie County (Jaeckle 1995, Maldonado & Young 1996).
Age, Size, Lifespan: Little is known about the maximum age and average lifespan of T. ignis colonies. In many areas, the fire sponge can encrust large surfaces with a layer about 1 cm thick (Kaplan 1988), and grow in vertical forms up to 30 cm in height (Voss 1980).
Abundance: The fire sponge is a common species in Florida waters, occurring in small numbers or large aggregations depending on environmental conditions and habitat type. Densities of T. ignis on rocks at the Fort Pierce Inlet of the IRL were recorded at approximately 9 individuals per square meter (Maldonado & Young 1996).
Reproduction: Most sponges are hermaphrodites, but they undergo sexual reproduction by producing either eggs or sperm exclusively over the course of a reproductive season or period (Ruppert & Barnes 1994). In addition, several species can regenerate lost or damaged tissue, and a few sponges can reproduce asexually through budding.
However, little is known about these processes in T. ignis, and the majority of studies have focused on sexual reproduction of the species. Eggs are produced by archeocyte or choanocyte cells, and are fertilized when the parent takes in sperm from nearby sponges through the incurrent pore. In T. ignis, fertilized eggs are brooded in the adult sponge until hatching. Larval release for fire sponge populations in the IRL occurs from late April through August, when coastal waters are warm (Maldonado & Young 1996).
Embryology: Numbers of brooded eggs are highest at the beginning of a reproductive period, with 5 mm2 x 1mm sections of tissue holding approximately 8-12 eggs (Maldonado & Young 1996). After hatching, larvae are released from the parent through the ectosome, or dermal layer. Populations of T. ignis in the IRL usually undergo massive larval release, followed by small releases of 15-20 larvae over a few days (Maldonado & Young 1996). Each larva is orange-red in color, approximately 800 x 600 µm in size, and weighs about 17 µg (Jaeckle 1995). They are uniformly ciliated except for the posterior end, which is bare. These cilia and body contractions allow larvae to swim in a slow corkscrew motion for the next 48 to 72 hours, after which they settle in shaded areas, usually near adult T. ignis (Maldonado & Young 1996). Fusion of larvae and juveniles is common during settlement.
Temperature & Salinity: Little information is available on the environmental tolerances of T. ignis. However, the range and distribution of the species suggests it prefers warm brackish to marine waters.
Trophic Mode: Like other sponges, T. ignis is a filter feeder. The sponge draws in water through incurrent pores using flagellated cells called choanocytes (Ruppert & Barnes 1994). Suspended particles between 0.1 and 1.5 µm are taken in, mostly consisting of bacteria and other organic material. The choanocytes partially digest the food material which is then transferred to other parts of the sponge for final assimilation.
Predators: Although the color and chemical compounds of T. ignis appear to act as predation deterrents, a few species find the sponge palatable, including: parrotfish; the cushioned sea star, Oreaster reticulatus; and the gray angelfish, Pomacanthus arcuatus (Wulff 2006).
Associated Species: Little information exists about obligate associations of T. ignis. However, as inhabitants of a variety of coastal ecosystems, the fire sponge is associated with several organisms common to seagrass beds, mangroves, rocky shores and nearshore reefs.
Special Status: Biomedical Applications
Economic Importance: In 1984, a potent antitumor compound, known as tedanolide, was isolated from the fire sponge (Schmitz et al. 1984). Over the past 20 years, the growing interest in this chemical compound has prompted the total synthesis of tedanolide for use in clinical trials, no longer requiring the use of the sponge for compound production.
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