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title = "The Mantis Shrimp: A Field Guide"
language = "en"
header_right = "Stomatopoda - Field Guide"
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Mantis shrimp are marine crustaceans of the order Stomatopoda: burrowing ambush predators famous for the fastest limb strike in the animal kingdom and for one of the most elaborate visual systems ever described.
Handle with care.
A large smasher can split a fingernail (hence the common name "thumb splitter") and has been known to crack the glass of an aquarium. Never pick one up by hand.
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This profile covers:
- how the group is classified and where it lives (sections [#classification] and [#habitat]);
- the mechanics of the predatory strike and the animal's vision (sections [#strike] and [#vision]);
- notable species and how to record a field observation (section [#record] onwards).
{ label = "classification" }
The mantis shrimp belong to the order Stomatopoda within the class Malacostraca of the crustaceans. Around 450 species have been described, none of them a true shrimp. They diverged from other malacostracans over 340 million years ago, and the lineage's distinctive raptorial limbs are already recognisable in the fossil record.
The body is divided into a shielded head and thorax and a broad, muscular tail. The features most worth knowing in the field are:
- a pair of stalked, independently mobile compound eyes;
- the folded raptorial appendages: a club in smashers, a barbed spear in spearers;
- the telson, the armoured tail plate used to block the burrow entrance.
{ label = "strike" }
Stomatopods fall into two camps. Smashers wield a folded, club-like appendage that they release like a spring; spearers deploy a barbed limb to impale soft-bodied prey.
A smasher's club accelerates so violently that it boils the water in front of it, collapsing into a cavitation bubble whose implosion delivers a second blow even if the first misses. The strike is among the fastest movements known in any animal, and it is aimed by the visual system described in section [#vision].
The energy comes not from muscle alone but from a saddle-shaped spring in the limb that is compressed and then latched, storing energy that is released all at once, the same principle as a crossbow. The club itself is a layered composite that resists the shattering forces it generates, and has inspired the design of impact-resistant materials.
{ label = "vision" }
Each eye moves independently and carries three regions that view the same point, giving the animal trinocular depth perception in a single eye.
Where humans have three colour receptors, a mantis shrimp may have as many as sixteen, and can also detect both linear and circular polarised light, a capability found in no other animal.
Curiously, all those receptors do not make it a better judge of subtle colour differences than we are. Current thinking is that the eye reads colour more like a set of sensors than a mixing palette, trading fine discrimination for a very fast, low-effort readout, useful for an animal that must decide in milliseconds whether to strike.
Smashers specialise in hard-shelled prey (crabs, snails and molluscs), which they batter open with repeated blows. Spearers ambush soft, fast prey such as fish and shrimp, flicking the barbed limb out faster than the eye can follow.
Most mantis shrimp are solitary and fiercely territorial, defending a burrow or rock crevice. Some species, however, are monogamous and may share a burrow with the same partner for up to twenty years, with the pair coordinating to defend and maintain their home.
They are unexpectedly communicative animals. Rivals settle disputes with a ritualised meral spread in which they flare their coloured limbs to warn off an opponent before any blow is struck. Several species also bear patches that fluoresce under the blue light of deeper water, thought to signal to others of their kind.
Their reputation among people is mixed. Fishermen know them as "prawn killers" for the catch they raid, and divers as "thumb splitters" for the wounds a startled smasher can inflict. A few of the larger, more colourful species are prized by aquarists and kept, warily, in tanks of their own.
{ label = "habitat" }
Mantis shrimp are found in shallow tropical and subtropical seas:
the Indo-Pacific from East Africa to Hawaii, the Red Sea, the Mediterranean and eastern Atlantic, and the tropical western Atlantic from Florida to Brazil
Most species live from the intertidal zone down to a few tens of metres, though some range considerably deeper. Nearly all are tied to a shelter: spearers tend to dig vertical burrows in sand or mud, while smashers occupy cavities in coral rubble and rock, enlarging and defending them over a lifetime.
| common name | species | strike | max. length | |
|---|---|---|---|---|
| 1 | Peacock mantis shrimp | Odontodactylus scyllarus | smasher | 18 cm |
| 2 | Zebra mantis shrimp | Lysiosquillina maculata | spearer | 40 cm |
| 3 | Purple-spot mantis shrimp | Gonodactylus smithii | smasher | 10 cm |
| 4 | Caribbean rock mantis shrimp | Neogonodactylus oerstedii | smasher | 7 cm |
| 5 | Spottail mantis shrimp | Squilla mantis | spearer | 20 cm |
| 6 | Giant mantis shrimp | Hemisquilla californiensis | smasher | 30 cm |
| 7 | Ciliated false squilla | Pseudosquilla ciliata | spearer | 10 cm |
Representative figures for the smashers' strike and for vision:
| attribute | value | unit | notes | |
|---|---|---|---|---|
| 1 | Peak strike speed | 23 |
m/s | club tip, peacock mantis shrimp |
| 2 | Strike acceleration | 10400 |
g | on the order of a .22 bullet |
| 3 | Peak strike force | 1500 |
N | enough to crack aquarium glass |
| 4 | Strike duration | 2.7 |
ms | followed by a cavitation bubble |
| 5 | Photoreceptor types | 16 |
- | against three in the human eye |
{ label = "record" }
When you observe an animal in the field, try to record the following:
- Photograph the raptorial appendages so the strike type (smashing club or spearing barb) can be determined later.
- Record the burrow entrance and the surrounding substrate (sand, rubble or coral).
- Note the water temperature and the depth at which the animal was observed.
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A complete identification record includes:
a. a dorsal photograph showing the full body; b. an estimate of the total body length; c. the coordinates and depth of the sighting.
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| Observer | Costa, R. | | Location | Lembeh Strait, Indonesia | | Date | ________ | | Depth | ________ | | Signature | ________ |
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I, ___(160), identified the specimen above as ___(160).
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Return completed records to:
Stomatopod Survey, Marine Field Station
Lembeh Strait, North Sulawesi