The black-faced blenny (Tripterygion delaisi) is a small benthic fish from the family Tripterygiidae (triplefin-blennies). It occurs at depths of 3 to 40 metres (9.8 to 131.2 ft) and lives on the substrate under large rocks, cliffs or other overhangs.
The species was described in 1970 by Jean Cadenat and Jacques Blache, from a type series collected at Gorée in Senegal by Michel Delais of Institut Fondamental d'Afrique Noire in Dakar, who is honoured in its specific name.
Pl
PlanktivoreA planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Phytoplankton are usually photosynthet...
Ca
CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
Ov
OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
So
SolitaryNo
Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
B
starts withLike all triplefin-blennies, T. delaisi has three dorsal fins and can hence easily be distinguished from members of the families Blenniidae (1 dorsal fin) and Gobiidae (2 dorsal fins) that have a similar live-style and general appearance. It has a peaked head and short tentacles above the eyes.
The common name yellow black-faced blenny derives from the colouration of territorial males during the breeding season: their body becomes yellow and their head turns black; during a territorial fight the colouration of the head changes to a grey colour as a sign of aggression. Non-territorial males, females, and juveniles are cryptically coloured and are grey-brown with five dark and broad dorso-ventral bands between the head and the tail. Outside the breading season, males and females can only be told apart with certainty by dissection.
The black-faced blenny can grow up to 8 centimetres (3.1 in) long. On average, territorial males (6.1 centimetres (2.4 in)) are slightly larger than non-territorial males (4.7 centimetres (1.9 in)) and females (5.0 centimetres (2.0 in)). Individuals caught in deeper water are generally larger than those captured in shallow waters.
T. delaisi inhabits 2 disjunct areas: 1. the western Mediterranean Sea and adjacent parts of the Atlantic Oceans from north to the British Isles and south of Casablanca and Morocco, 2. western tropical Africa north to Senegal and the Macaronesian islands.
It lives at depths between 3 and 40 metres (120 and 1,570 in) but is most common at depths between 6 and 25 metres (20 and 82 ft). It prefers shaded, dark areas, such as shady rock faces, overhangs and crevices . In the Atlantic Ocean T. delaisi can be observed without cover even in shallow waters, but in the Mediterranean Sea it can only be seen without cover below depths of 10 metres (33 ft). This phenomenon can be explained through a lack of competition: In the Mediterranean Sea T. tripteronotus occurs in depth from 0 to 5 metres (0 to 16 ft) whereas in the Atlantic Ocean, where T. tripteronotus is absent, this niche is free to occupy.
The territorial males of T. tripteronotus and T. melanurus both have a red body with a black head, a signal that is strong in shallow waters where red light is still abundant, but becomes less and less striking with increasing depth due to the high absorption of long wavelengths in water. This might explain why T. delaisi only occurs below 5 metres (16 ft) in depth, whereas T. tripteronotus lives between 0 and 5 metres (0 and 16 ft): Males with a primarily red colouration can only successfully court for females where red light is present in the environment but in these shallow waters red is a stronger signal than yellow. Yellow males however, still exhibit a relatively striking colouration even at larger depths where they can successfully court for females.
T. delaisi is a carnivore that mainly feeds on small crustaceans, such as Harpacticoids, Tanaidaceans, Caprellidae, and Amphipods. It cannot bite pieces out of its prey and thus cannot eat prey larger than its mouth. Defecation takes 1 to 2 s.
Prior to the capture, T. delaisi looks at the prey item for several seconds; meanwhile the first dorsal fin rhythmically twitches about twice per second. The capture is achieved by a sudden inhaling movement, which sucks the prey into the mouth. If the prey is attached to the substrate, it is torn loose by a sideward movement of the head.
Overall the territorial period of the males lasts from beginning of February until beginning of September, but the average duration of the territorial period per male was 47.1 days (in Corsica ). Male T. delaisi show territorial behaviour for 2 consecutive years. Spawning takes place from mid of March until June.
The male territories are located on the lower side of overhanging cliffs and rocks and have a diameter of around 1 metre (3.3 ft). If two territories are visually hidden from each other their centres can be as close as 0.5 metres (20 in). Within the territory a smaller area of 20 by 20 centimetres (7.9 in × 7.9 in) is used for nesting. Male T. delaisi are able to find their territories from distances up to 200 m away.
The female leaves after spawning and only the male takes care of the eggs. Fanning fresh water at the eggs for increased oxygen supply, a widely distributed behaviour in most fish families, is not displayed by T. delaisi. Nevertheless, the male cleans the eggs by frequent plucking and defends them against predators. The main threat to T. delaisi eggs are blenniids, juvenile sparids, Crenilabrus species, crabs and sea urchins. Although some of these predators are much larger than the defending male, a nest is only rarely preyed upon when defended by a male; when removed all eggs are normally eaten within half an hour. Fish predators are bitten in their flanks and fins, crabs in their eye-stalks and successfully driven away. Although sea urchins are also attacked by T. delaisi males, they are the only threat a guarding male cannot defend his eggs against.
Dead eggs are removed by the male and usually eaten. If a dead egg is still attached to substrate it is carried away from the rest of the eggs and spat out. When accidentally plucking a hatching egg, the male swims upwards and spits the larva out, giving it a better chance of being carried away by the water currents.
