Species Description: The seaweed blenny, Parablennius marmoreus, is one of several species of combtooth blennies belonging to the family Blenniidae.
This combtooth blenny has 35-43 comb-like incisors (Lindquist & Dillaman 1986) in addition to upper and lower canines (Ditty et al. 2005). The body of P. marmoreus is tan to rusty orange with scattered or clustered dark brown spots and a bronze area on the top of the head (Robins & Ray 1986). A wide dusky stripe extends from the eye toward the caudal fin on each side, most visible above the pectoral fin and usually fading on the rear of the body. The ventral surface of the head is whitish. The filamentous appendage above each eye, called the cirrus, is branched in this species. Fin rays and other meristic counts are as follows: dorsal spines = 6-7; dorsal soft rays = 17-18; total anal elements = 21-22; total vertebrae = 36; pelvic spines and rays = 1 and 3, respectively; pectoral fin rays = 14; and upper, primary and lower caudal fin rays = 6, 13 and 6, respectively (Ditty et al. 2005).
Potentially Misidentified Species: Several species of combtooth blennies inhabit the IRL and surrounding coastal waters. Of these, the most closely related and morphologically similar species are the pearl blenny, Entomacrodus nigricans; and the molly miller, Scartella cristata (Robins & Ray 1986). The dorsal fin of the pearl blenny is deeply notched, with the spinous section low and straight-edged. The body is brown with irregular large dark brown bars, blackish and pearly white spots. Dark bands are also present on the lips and cheeks. The maximum size of E. nigricans is 10 cm, slightly larger than the seaweed blenny. The molly miller also reaches lengths of 10 cm, but has a row of comb-like cirri down the middle of the head anterior to the dorsal fin. Like P. marmoreus, the cirrus above each eye is branched. The body is olive brown with darker markings and occasional pearly white spots, and the caudal fin is usually barred.
Regional Occurrence: The range of the seaweed blenny extends from New York to the northern Gulf of Mexico, Bermuda, and the Bahamas to northern South America (Robins & Ray 1986). Like other combtooth blennies, P. marmoreus can be found in rocky intertidal zones, seagrass beds, oyster reefs, or among litter such as cans and bottles strewn on the benthos. The seaweed blenny is also found on nearshore reefs, around buoys and pilings, and offshore around oil and gas platforms (Ditty et al. 2005).
IRL Distribution: The IRL, the seaweed blenny occurs in several habitats. However, it seems to be most abundant around inlets where it is associated with rocky seawalls, jetties, buoys and pilings.
Age, Size, Lifespan: Information concerning the maximum age and average lifespan of P. marmoreus is lacking. Growth rates vary with environmental conditions, food availability and other factors. The maximum reported size for the seaweed blenny is 8.5 cm (Robins & Ray 1986).
Abundance: Little information is available on the abundance of P. marmoreus. However, surveys reported up to 30 individuals throughout 27 500m3 transects on the artificial reefs of the Flower Garden Banks National Marine Sanctuary located in the northwestern Gulf of Mexico (Rooker et al. 1997).
Reproduction: Like most other blennies, egg deposition and development occurs on the benthos. After fertilization is complete, all the females of a single male mate deposit eggs on a protected surface, such as: empty bivalve shells, holes in rocks, sponges, or inside discarded cans (Peters 1981). The parental male then guards the clutches until hatching (Labelle & Nursall 1992).
Embryology & Larval Development: Information regarding the gestation period and embryology of P. marmoreus is lacking. Larvae range between 5.8 and 16.0 mm in length, bearing an average of 9 teeth. Once the larvae settle at a length of 19.0 to 20.5 mm, they have up to 22 teeth (Ditty et al. 2003, 2005). Pectoral fin pigmentation is generally absent until just before settlement (Ditty et al. 2005).
Temperature & Salinity: Little temperature and salinity tolerance data are available for the seaweed blenny. Because it ranges from temperate to tropical coastal habitats, it is likely that environmental tolerances of this species are quite large.
Trophic Mode: The seaweed blenny uses its beak-like lower jaw to pick at organisms on the benthos and among fouling communities. Common prey items and other foods include a variety of polychaetes, crustaceans, hydroids and algae (Lindquist & Dillaman 1986, Longley & Hildebrand 1941, Randall 1967).
Predators: While information regarding specific predators of the seaweed blenny is scarce, it is likely that this species is preyed upon by larger demersal fishes and crustaceans such as crabs and lobsters.
Activity Time: Like other combtooth blennies, P. marmoreus is diurnal, actively feeding and engaging in other behaviors during the day (Robins & Ray 1986, Rooker et al. 1997).
Associated Species: No known obligate associations exist for P. marmoreus. However, as inhabitants of a variety of coastal ecosystems, seaweed blennies are associated with several organisms common to seagrass beds, oyster reefs, rocky intertidal zones and nearshore reefs.
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Ditty, JG. 2002. Ontogeny and intervals of development in five reef-associated species of blenny from the northern Gulf of Mexico (Teleostei: Blenniidae). PhD Dissertation. LA State Univ. USA. 168 pp.
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