TankBud

Staghorn hermit crab

Manucomplanus varians

Also known as Antler staghorn hermit, Antler hermit crab, Staghorn hermit

SaltwaterCrab

Care at a glance

Temperature
68–77°F
20–25°C
pH
8.1–8.4
Adult size
0.8 in
2 cm
Minimum tank
26 gal
100 L
Temperament
Peaceful
Social behavior
Solitary
Own kind
One per tank
Tankmates
With caution
Swim level
Bottom
Diet
Omnivore
Difficulty
Difficult
Breeding
No record
Rarity
Rare
Reef safe
Reef safe with caution
Family
Paguridae
Origin
Eastern Pacific, Gulf of California to Panama

Overview

The staghorn hermit crab is a small, peaceful hermit crab for the sand of a cool, dimly lit saltwater tank. It is for experienced keepers.

Did you know

The staghorn hermit crab never trades up to a bigger shell as it grows. Instead, the hydrocoral Janaria mirabilis dissolves its snail shell away and grows into an antler-shaped home around it.

Caring for the staghorn hermit crab

Give the staghorn hermit crab a mature tank of 26 gal (100 L) or more, with open sand. Use low to moderate light and gentle to moderate flow.

Keep the water at 68 to 77°F (20 to 25°C) with a pH of 8.1 to 8.4. Those values are a best guess from its depth range, since no source gives a tested figure, and cooler is the safer side.

The crab scavenges algae, detritus and meaty leftovers. Feed it dried seaweed and small meaty foods. Feed the hydrocoral daily under low light, with fine powdered or liquid plankton foods meant for non-photosynthetic corals. Even then the hydrocoral often dies within months, leaving a plain hermit in a dead skeleton.

It is peaceful and leaves fish and corals alone, yet it is reef safe only with caution. Its living shell stings, and is stung by, any corals and anemones it brushes against, so keep them out of its reach. The hydrocoral also needs feeding that most reef tanks do not provide. Keep one per tank, since two fight and will abandon their hydrocoral homes for any ordinary shell you offer.

It may not be able to right itself if it tips over, because of its top-heavy home. Keep it away from ledges and boisterous tank mates, and check on it daily.

Good to know

Manucomplanus varians is a small pagurid hermit crab, described by Benedict in 1892. The San Diego Natural History Museum gives it a carapace of just 6 mm. Retailers quote larger figures because they measure it with the shell. Janaria mirabilis is a colonial hydrozoan with a hard calcareous skeleton and photosynthetic zooxanthellae. It settles on the shell while the crab is young, and its branched house can reach about 5 cm across. The crab seals the entrance with its claw and, the museum notes, trims the doorway as the colony grows. Some shells are overgrown by bryozoans instead.

In the wild

The staghorn hermit crab comes from the eastern Pacific, from Magdalena Bay and the Gulf of California south to Panama. Most trade animals are trawled in the Sea of Cortez. It lives on mixed sand and rock bottoms from 6 to 183 m, so it sees cooler, dimmer water than a reef flat. Retailer pages that call it Indo-Pacific are wrong.

Common questions

What size tank does a staghorn hermit crab need?

A staghorn hermit crab needs at least 26 gal (100 L). It spends most of its time in the bottom.

What temperature and pH does a staghorn hermit crab need?

A staghorn hermit crab is comfortable at 68–77°F (20–25°C) with a pH of 8.1–8.4.

What does a staghorn hermit crab eat?

A staghorn hermit crab scavenges algae, detritus and meaty leftovers. Feed it dried seaweed and small meaty foods, and feed its hydrocoral home daily with fine plankton foods.

How big does a staghorn hermit crab get?

An adult staghorn hermit crab reaches about 0.8 in (2 cm).

Related species