Breeding the Sally Lightfoot Crab (Percnon gibbesi)
Percnon gibbesi is a fast herbivorous crab and a notorious Mediterranean invader. Females brood eggs and release long-lived planktonic larvae, so home breeding is not achievable.
Overview
Percnon gibbesi is a flat, fast-moving crab of the family Percnidae with a carapace about 30 mm wide and spined walking legs. It is native from California to Chile in the Pacific and Florida to Brazil in the Atlantic, and is strictly herbivorous; in the Caribbean it associates with the sea urchin Diadema antillarum. It is described as the most invasive decapod to enter the Mediterranean, first recorded at Linosa, Sicily in 1999.
Sexing
Sexes are distinguished by abdominal shape, and a gravid female is recognized by the egg mass carried beneath the abdomen on the pleopods. Egg-carrying females have been recorded off West Africa between February and April and in August.
Conditioning
An algae-rich environment supports this herbivore, but adults become predatory as they grow and are best kept singly with robust tankmates. No documented protocol reliably induces or completes reproduction in a home reef, because the larvae are planktonic and cannot be reared in a display.
Breeding Setup
No practical home breeding setup exists. The female broods fertilized eggs until hatching, then releases larvae into the water column. These larvae are planktonic and long-lived, a trait that contributes to the species' invasiveness, and they require open-water rearing conditions.
Spawning & Larvae
Hatched larvae enter the plankton and remain there for an extended period, developing through molts before settling. This long-lived planktonic phase is exactly what makes the species so good at colonizing new regions and what makes captive rearing impractical.
Common Challenges
- Long-lived planktonic larvae are removed by filtration and skimming.
- Larvae require continuous planktonic food over a prolonged period.
- Adults turn predatory and may eat tankmates and invertebrates.
- Never release this invasive species into the wild.