Devil crab (Zosimus aeneus)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Arthropoda · Class: Malacostraca · Order: Decapoda · Family: Xanthidae · Genus: Zosimus.

Accepted name: Zosimus aeneus · Authority: (Linnaeus, 1758) · Taxonomic status: accepted · AphiaID: 209076.

Synonyms and superseded combinations recorded for this taxon: Cancer aeneus Linnaeus, 1758; Cancer amphitrite Herbst, 1801; Cancer floridus Herbst, 1783; Zozimus aeneus (Linnaeus, 1758); Zozymus aeneus (Linnaeus, 1758).

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=209076 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Zosimus aeneus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 10 cm · Depth range: 0–10 m · Habitat zone: reef-associated · Vulnerability index: 10 of 100 · Fishery importance: commercial · Aquarium trade: never/rarely.

SeaLifeBase notes: Adults occur in coral reefs, hidden under rocks during the day. Nocturnal (Ref. 128968). The shell and flesh of this species contain neosaxitoxin, saxitoxin, and tetrodotoxin (Ref. 107779, 128965) which have been proven to be fatal when ingested (Ref. 128965). Intertidal to subtidal (Ref. 106854). Members of the family Xanthidae range from being algal scrapers to aggressive predators (Ref. 103027).

Source: SeaLifeBase species summary (SpecCode 21465) — https://www.sealifebase.se/summary/Zosimus-aeneus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

490 georeferenced occurrence records for Zosimus aeneus are published through GBIF from 49 countries or marine areas. The map above plots 176 distinct locations from a sample of 490 records, omitting 29 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Australia (85); Papua New Guinea (62); French Polynesia (35); Marshall Islands (32); Indonesia (31); Chinese Taipei (26); India (20); New Caledonia (19); Philippines (18); Japan (17); Solomon Islands (13); Kiribati (10); Saudi Arabia (9); Cook Islands (8); Northern Mariana Islands (8).

Marine regions with a valid WoRMS distribution record: Somali Exclusive Economic Zone; West Indian Ocean; Red Sea; Tanzanian Exclusive Economic Zone; Mozambican Exclusive Economic Zone; East Africa; Madagascar; South Africa (country); Seychellois Exclusive Economic Zone; Mayotte Disputed area: France / Comoros; New Caledonian Exclusive Economic Zone; Wallis and Futuna Exclusive Economic Zone; French Polynesian Exclusive Economic Zone; Réunion Exclusive Economic Zone.

Source: GBIF Occurrence Search (taxonKey 2227782) — https://www.gbif.org/occurrence/search?taxon_key=2227782&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=209076 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Description and natural history (Wikipedia)

Zosimus aeneus was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. It was transferred to the genus "Zozymus" by James Dwight Dana in 1852, which was replaced with Zosimus by Mary J. Rathbun in 1907. It is the type species of the genus Zosimus.

Zosimus aeneus reaches a size of 60 x 90 mm. It is "a well known brightly coloured and strikingly patterned species": its carapace and legs (including the claws) are marked with a characteristic pattern of red or brown patches on a pale brown or cream background. The carapace is deeply grooved, and the walking legs have prominent crests.

Zosimus aeneus is found across a large part of the Indo-Pacific, from South Africa to the Red Sea, and as far east as Japan, Australia and Hawaii.

It lives on reef flats in the intertidal zone.

Both the shell and the meat of Zosimus aeneus contain significant concentrations of neurotoxins including tetrodotoxin and saxitoxin. Tetrodotoxin (TTX) is the compound responsible for the toxicity of puffer fish, while saxitoxin (SXN) is the best known of several related neurotoxins that cause paralytic shellfish poisoning (PSP). Both are absorbed through the gastrointestinal tract and interfere with sodium channels in the membranes of nerve cells.

Poisoning with Z. aeneus can be fatal; one man in Timor-Leste died hours after consuming the crab, having received a dose equivalent to 1–2 μg saxitoxin per kilogram body mass. The flesh of Z. aeneus is reported to be ingested by inhabitants of the Pacific Islands with the intention of committing suicide.

Z. aeneus is considered the most poisonous crab in the Philippines, with 50% of intoxication cases being fatal. Studies determined that individual specimens contained in excess of 3000 MU/g of saxitoxin, a lethal amount for humans that resulted in 12 fatalities in Negros Island in the 1980s. In February 2021, two children in Cagayan died after eating Z. aeneus caught by their father. In February 2026, a food vlogger in Palawan allegedly died after feasting on several Z. aeneus for her social media channel.. The family soon clarified that Amit did not create any video content concerning the crab she'd eaten on that fateful day, and was unaware that this crab, gathered by others, was harmful.

Source: Wikipedia: Zosimus aeneus — https://en.wikipedia.org/wiki/Zosimus_aeneus (CC BY-SA 4.0). Accessed 2026-09-23.

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