The yeti crab (Kiwa hirsuta) is one of the most extraordinary deep-sea discoveries of the 21st century — a pale, blind crustacean covered in long, silky, hair-like setae that give it the appearance of a tiny, fuzzy yeti. Discovered in 2005 at a hydrothermal vent field in the South Pacific, the yeti crab was so different from known crustaceans that scientists created an entirely new family to classify it. It has since revealed remarkable behaviors and adaptations that upend assumptions about how animals can survive at the extreme margins of life.
What Is the Yeti Crab?
The yeti crab is a squat lobster — more closely related to hermit crabs and lobsters than to true crabs — belonging to the newly created family Kiwaidae. The genus Kiwa is named after the Polynesian goddess of shellfish; hirsuta means “hairy” in Latin. The common name comes from the Yeti — a mythical hairy creature — apt for an animal that appears covered in white fur.
The “fur” is not actually hair. It consists of dense mats of filamentous bacteria growing on specialized setae (bristles) covering the animal’s claws and body. This is not a mere quirk — the bacteria are central to the yeti crab’s survival strategy.
Where Do Yeti Crabs Live?
The original yeti crab species (Kiwa hirsuta) was found at the Easter Island Microplate in the South Pacific, at depths of approximately 2,200 meters, clustered around hydrothermal vents. Since 2005, additional species have been discovered:
- Kiwa puravida — discovered in 2006 off Costa Rica at cold seeps (methane seeps rather than hydrothermal vents) at 1,000 meters
- Kiwa tyleri — the “Hoff crab,” discovered in 2011 at the East Scotia Ridge in the South Atlantic, forming enormous colonies of hundreds of thousands around Antarctic hydrothermal vents at 2,400 meters
- Kiwa araonae — discovered in 2016 in the deep waters off Antarctica
All species live in chemosynthetic environments — hydrothermal vents or cold methane seeps — where sunlight-independent ecosystems thrive on chemical energy.
What Do Yeti Crabs Eat? A Bacterial Farm on Their Arms
Yeti crabs farm bacteria. The filamentous bacteria growing on their setae are chemosynthetic — they derive energy from the hydrogen sulfide and methane emitted by hydrothermal vents, fixing carbon the way plants fix it from sunlight. The yeti crab cultivates these bacteria by waving its claws in the vent effluent, exposing the bacteria to the chemicals they need to thrive.
It then eats the bacteria by combing the setae with a specialized mouth appendage — effectively harvesting a crop it has grown on its own body. This relationship makes the yeti crab both farmer and harvester, with its hairy claws functioning as a portable bacterial garden.
Some species may also consume other vent organisms including mussels, polychaete worms, and the bacterial mats that coat vent surfaces.
How Yeti Crabs Survive at Hydrothermal Vents
Hydrothermal vents are extreme environments — superheated water (up to 400°C at the vent opening, cooling rapidly to just above freezing within centimeters), high pressure, complete darkness, and high concentrations of toxic chemicals including hydrogen sulfide. Yeti crabs have evolved to exploit this environment rather than avoid it:
- No eyes: Yeti crabs are effectively blind — their eyes are vestigial, covered by a membrane. In total darkness, functional eyes provide no advantage.
- Temperature tolerance: They position themselves at precise locations within the vent gradient where temperature is optimal — not too hot to survive, warm enough to support bacterial growth on their setae
- Dense aggregations: Kiwa tyleri forms remarkable “piles” of thousands of individuals stacked several animals deep around vent openings — thought to be driven by competition for optimal temperature zones
- Chemosynthetic dependence: The entire food web is independent of sunlight — energy flows from geological chemical processes rather than photosynthesis
Yeti Crab Size and Appearance
- Body length: Approximately 15 cm for K. hirsuta; species vary
- Color: Pale yellowish-white — no pigmentation needed in complete darkness
- Claws: Long, heavily setae-covered claws that carry the bacterial colonies
- Eyes: Vestigial — covered by a membrane, non-functional
- Setae: Long, silky filaments covering claws and sometimes the thorax — the defining visual characteristic
Key Facts
- Scientific name: Kiwa hirsuta (type species); genus Kiwa has 4+ species
- Family: Kiwaidae — created specifically for this genus in 2005
- Discovery: 2005, Easter Island Microplate, South Pacific
- Depth: 1,000–2,400+ meters
- Habitat: Hydrothermal vents and cold seeps
- Diet: Bacteria farmed on their own setae; possibly other vent organisms
- Eyes: Vestigial — blind
- Body length: ~15 cm
Frequently Asked Questions
Why is the yeti crab hairy?
The “hair” consists of specialized bristles (setae) that host colonies of chemosynthetic bacteria — the yeti crab’s primary food source. The setae provide surface area for bacterial growth, and the crab “farms” them by waving its claws in the hydrogen sulfide-rich vent water the bacteria need to survive.
Are yeti crabs edible?
They live at 2,000+ meters depth with no commercial fishery — they are far too deep and rare to be commercially exploited. There is no information on edibility, and no reason to pursue it. They are scientifically significant as a species, not a food source.
How was the yeti crab discovered?
The yeti crab was discovered on March 7, 2005, during a research expedition to the Easter Island Microplate using the submersible Alvin. The research team, led by Michel Segonzac, Robert Vrijenhoek, and others, found a new vent field and collected specimens that proved to be an entirely unknown family of crustaceans — one of the most significant deep-sea zoological discoveries in decades.
How do yeti crabs reproduce?
Little is known about yeti crab reproduction. Females with eggs have been found moving away from vent fields — possibly migrating to cooler, deeper water where eggs can develop away from the intense competition and temperature extremes near the vents. After larvae hatch and develop, juveniles return to vent environments.