Blue Beaked Shellbreaker
Gracilirostrum conchaedelendii is a small Regalipinninid Hijerakid amphibian from the parasitic Iron-Mussel reefs of north Meadow Island; the animal barely reaches 10 cm in length and its colours and playful nature make it one popular little critter for scuba divers to interact with.
The amphibian feeds on the Iron-Mussels composing the reef encrusting the bigger underlying armoured plant reef; to hunt, the animal uses the extremely sharp and thin beak to cut through the seal between the two valves of the Iron-Mussels, much like a scalpel cuts through bone, forcing them open by exerting force with the jaw on the beak, which acts as a lever and exposes the mollusc inside to the amphibian; G. conchaedelendii then uses the spoon-shaped end of the beak to scoop the prey from inside the shell.
Quite the social creature, this animal lives in large schools of up to a hundred specimens subdivided into smaller uni gender units of five to ten amphibians, each unit has a territory but they reunite with the rest of the colony each night to sleep in the communal nest, where they rest and interact with other groups; young specimens will follow these groups in an alternate fashion, each day following a different one, observing hunting tactics and movements of the mature individuals and learning the tactics used by many groups to bring to the next generation observing them.
Quite popular in aquariums, the species has been thoroughly bred in captivity and is now available in different morphs.
Basic Information
Anatomy
- Head very high with a very thin and sharp beak, cheeks very round; eyes very large compared to the body.
- body very high and thin.
- Dorsal fin I and II leaf shaped, Dorsal III longer, almost veiled.
- Anal I and II stubby and rounded; Anal I moved frontally to the same Height as the Pectoral and Dorsal I fins.
- Gill tail very short terminating in a very small Gill Fan with very low ridges and a very smooth caudal drop.
Genetics and Reproduction
Polygynous species.
G. conchaedelendii mates in the Summer; the various subunits of the species mate with adjacent groups of the opposing sex, with sexual selection dictated by how fast an amphibian mates as there are no mating dances or selective displays, the only thing to stop another male from mating with a female is if this female has already been fertilized; a quick male can hope to fertilize up to three females in a single group.
After the first round of mating has passed, the females will lay the eggs in the underlying plant reef.
In the evening, when the groups reunite with the colony, the second round of mating happens, helping genes to spread out evenly throughout the entire colony instead of only keep the gene pool localized; this second batch of eggs are laid inside the nest and are more valued by the colony than the first batch.
When the hatchlings from the first batch are born, four weeks after the eggs have been laid, they get drove away by the colony, who only keeps the hatchlings from the second batch.
The colony will take in wandering hatchlings from the first batch of another colony; it is thought this mechanism is a way for the species to spread its genes outside of the colonial territory, mixing some new genes every year and avoiding consanguinity from onsetting.
Growth Rate & Stages
Ontogeny not very marked in the species.
Loss of natal aculeus two days after hatching.
Ecology and Habitats
Epipelagic species found at depths between 0 and 50 m.
Lives in parasitic Iron-Mussel reefs encrusting the underlying true reef of armored plants; finds shelter in the under-reef if threatened outside of the nest.
Dietary Needs and Habits
Predatory animal feeding on encrusting Iron-Mussels.
An entire subunit can open up a mature one as a group effort but they otherwise eat younger specimens.
Biological Cycle
Periannial creature with few dips in activity year long.
Additional Information
Social Structure
An average colony of the species is a hundred amphibians strong, divided into several subunits of five to ten specimens of the same gender.
Each day the subunits return to the colonial nest, where they socialize and interact with the rest of the colony.
Different colonies exchange young specimens and sometimes they converge and become one bigger colony if a bigger potential nest is found.
In captivity the species lives in small smaller colonies than in the wild, with groups as small as being composed of only ten specimens; the species won't form big colonies if not in specialized tanks; this behaviour seems to be a direct consequence of restricted spaces and food availability, which suggests the species is capable of properly assessing resources and manage both them and the group size accordingly.
Experiments on captive individuals have been made to demonstrate this concept; as the food provided diminished, the colony got rid of the weaker individuals, driving them away from the colonial territory, optimizing resource management and selecting the stronger individuals for the next generation; researchers are still looking for similar behaviour to be demonstrated in the wild.
Domestication
Often kept in private aquariums for the colours and fplayful nature.
They are a suggested pet for beginners and children.
The most popular morphs found on the market as of the time of writing are the Ghost White, Black Shadow and Green Blast.
Uses, Products & Exploitation
Of major interest in the pet trade, although most specimens found on the market are bred in captivity.
Sometimes found in local markets in the mixed hauls of animals good for chum or for broths, otherwise not eaten alone.
Geographic Origin and Distribution
Perception and Sensory Capabilities
Good eyesight, poor hearing
Symbiotic and Parasitic organisms
In symbiosis with the underlying reef; they eat the encrusting Iron-Mussels in exchange for protection from threats.
Afflicted by drinker worms and often carriers of diseases, some of which transmittable to humans.
Scientific Name
Eoichthyia; Tartarosomnia; Hijerakia; Parahijerakida; Coronapinninoidea; Regalipinninidae ; Regalipinninae; Gracilirostrum; G. conchaedelendii
Lifespan
5 Years
Conservation Status
Least concern: No measures underway to protect this species
Population Trend: STABLE
Average Weight
25-200 gr
Average Length
Body Tint, Colouring and Marking
Body lime to bright green, cheeks yellow.
grey band going from the top half of the head down the body following the dorsum and belly, ending in an arrowhead shape near the throat.
belly and anal fins orange/yellow/red.
beak bright to deep blue with lighter bands that go up to the base of the first dorsal fin.
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