![Spirama helicina-W-Thailand7810](https://upload.wikimedia.org/wikipedia/commons/6/6f/Spirama_helicina-W-Thailand7810.JPG)
Deimatic behaviour or startle display means any pattern of bluffing
behaviour
Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as wel ...
in an animal that lacks strong defences, such as suddenly displaying conspicuous
eyespots, to scare off or momentarily distract a predator, thus giving the prey animal an opportunity to escape.
The term deimatic or dymantic originates from the Greek δειματόω (deimatóo), meaning "to frighten".
Deimatic display occurs in widely separated groups of animals, including
moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s,
butterflies
Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...
,
mantises
Mantises are an order (Mantodea) of insects that contains over 2,400 species in about 460 genera in 33 families. The largest family is the Mantidae ("mantids"). Mantises are distributed worldwide in temperate and tropical habitats. They hav ...
and
phasmids among the insects. In the cephalopods, different species of
octopus
An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...
es,
squid
True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
s,
cuttlefish
Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone, which is used for control of ...
and the
paper nautilus are deimatic.
Displays are classified as deimatic or
aposematic
Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste o ...
by the responses of the animals that see them. Where predators are initially startled but learn to eat the displaying prey, the display is classed as deimatic, and the prey is bluffing; where they continue to avoid the prey after tasting it, the display is taken as aposematic, meaning the prey is genuinely distasteful. However, these categories are not necessarily mutually exclusive. It is possible for a behaviour to be both deimatic and aposematic, if it both startles a predator and indicates the presence of
anti-predator adaptation
Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avo ...
s.
Vertebrates including several species of frog put on warning displays; some of these species have
poison
Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
glands. Among the mammals, such displays are often found in species with strong defences, such as in foul-smelling
skunk
Skunks are mammals in the family Mephitidae. They are known for their ability to spray a liquid with a strong, unpleasant scent from their anal glands. Different species of skunk vary in appearance from black-and-white to brown, cream or ginge ...
s and spiny
porcupine
Porcupines are large rodents with coats of sharp spines, or quills, that protect them against predation. The term covers two families of animals: the Old World porcupines of family Hystricidae, and the New World porcupines of family, Erethizont ...
s. Thus these displays in both frogs and mammals are at least in part aposematic.
In insects
![Dolichodial](https://upload.wikimedia.org/wikipedia/commons/0/03/Dolichodial.svg)
Deimatic displays are made by insects including the praying mantises (
Mantodea
Mantises are an order (Mantodea) of insects that contains over 2,400 species in about 460 genera in 33 families. The largest family is the Mantidae ("mantids"). Mantises are distributed worldwide in temperate and tropical habitats. They ha ...
) and stick insects (
Phasmatodea). While undisturbed, these insects are usually well
camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...
d. When disturbed by a potential predator, they suddenly reveal their hind wings, which are brightly coloured. In mantises, the wing display is sometimes reinforced by showing brightly coloured front legs, and accompanied by a loud hissing sound created by
stridulation
Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...
. For example, the grasshopper ''
Phymateus
''Phymateus'' is a genus of grasshoppers of the family Pyrgomorphidae.
Description
Species of the genus ''Phymateus'' are African grasshoppers about long. Some species at maturity are capable of long migratory flights. They raise and rustle wi ...
'' displays red and yellow areas on its hind wings; it is also aposematic, producing a distasteful secretion from its thorax.
[ Similarly the threat display of the walking stick phasmid ('']Peruphasma schultei
''Peruphasma schultei,'' known as the black beauty stick insect, is a species of phasmid found in the Cordillera del Condor region of northern Peru. In the wild the insect feeds on ''Schinus'' plants, but will feed on privet, ''Aucuba japonica' ...
'') is not a bluff: the insect sprays defensive dolichodial
Dolichodial is a natural chemical compound with two aldehyde groups, which belongs to the group of iridoid
Iridoids are a type of monoterpenoids in the general form of cyclopentanopyran, found in a wide variety of plants and some animals. They ...
-like monoterpene
Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen funct ...
chemical compounds at attackers.
Among moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s with deimatic behaviour, the eyed hawkmoth (''Smerinthus ocellatus
''Smerinthus ocellatus'', the eyed hawk-moth, is a European moth of the family Sphingidae. The species was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''.
The eyespots are not visible in resting position, whe ...
'') displays its large eyespots, moving them slowly as if it were a vertebrate predator such as an owl
Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...
.[ Among ]butterflies
Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...
, the peacock butterfly ''Aglais io
''Aglais io'', the European peacock, more commonly known simply as the peacock butterfly, is a colourful butterfly, found in Europe and temperate Asia as far east as Japan. It was formerly classified as the only member of the genus ''Inachis'' ...
'' is a cryptic leaf mimic with wings closed, but displays 4 conspicuous eyespots when disturbed, in a display effective against insectivorous birds (flycatchers).
An experiment by the Australian zoologist A. D. Blest demonstrated that the more an eyespot resembled a real vertebrate eye in both colour and pattern, the more effective it was in scaring off insectivorous birds. In another experiment using peacock butterflies, Blest showed that when the conspicuous eyespots had been rubbed off, insectivorous birds (yellow buntings) were much less effectively frightened off, and therefore both the sudden appearance of colour, and the actual eyespot pattern, contribute to the effectiveness of the deimatic display.[
Some ]noctuid
The Noctuidae, commonly known as owlet moths, cutworms or armyworms, are a family of moths. They are considered the most controversial family in the superfamily Noctuoidea because many of the clades are constantly changing, along with the other f ...
moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s, such as the large red underwing
The red underwing (''Catocala nupta'') is a moth of the family Erebidae. The species was first described by Carl Linnaeus in his 1767 12th edition of ''Systema Naturae''.
This is a large (80 mm wingspan) nocturnal Palearctic (including ...
(''Catocala nupta''), are cryptic at rest, but display a flash of startlingly bright colours when disturbed. Others, such as many species of genus ''Speiredonia
''Speiredonia'' is a genus of moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximat ...
'' and ''Spirama
''Spirama'' is a genus of moths in the family Erebidae first described by Achille Guenée in 1852.
Description
Antennae usually minutely fasciculate (bundled) in the male. Tibia not hairy and mid-tibia spined. Palpi with second joint reaching ...
'', look threatening while at rest. Also saturniid moths of the genera ''Attacus
''Attacus'' is a genus of moths in the family Saturniidae. The genus was named by Carl Linnaeus in his 1767 12th edition of ''Systema Naturae''. '' and ''Rothschildia
''Rothschildia'' is a genus of moths in the family (biology), family Saturniidae first described by Augustus Radcliffe Grote in 1896.
Species are found in North America and South America from the United States to Argentina.
Species
*''Rothschil ...
'' display snake heads, but not from the frontal position.
Many arctiid moths make clicks when hunted by echolocating bats; they also often contain unpalatable chemicals. Some such as dogbane tiger moths (''Cycnia tenera
''Cycnia tenera'', the dogbane tiger moth or delicate cycnia, is a moth in the family Erebidae. It occurs throughout North America, from southern British Columbia to Nova Scotia southwards to Arizona and Florida. The species is distasteful and th ...
'') have ears and conspicuous coloration, and start to make clicks when echolocating bats approach. An experiment by the Canadian zoologists John M. Ratcliffe and James H. Fullard, using dogbane tiger moths and northern long-eared bats (''Myotis septentrionalis
''Myotis septentrionalis'', known as the northern long-eared bat or northern myotis, is a species of bat native to North America. There are no recognized subspecies. The northern long-eared bat is about 3–3.7 inches in length, with a wingspan ...
''), suggests that the signals in fact both disrupt echolocation and warn of chemical defence. The behaviour of these insects is thus both deimatic and aposematic.
File:Flügel Peruphasma schultei.jpg, Deimatic display of the phasmid ''Peruphasma schultei
''Peruphasma schultei,'' known as the black beauty stick insect, is a species of phasmid found in the Cordillera del Condor region of northern Peru. In the wild the insect feeds on ''Schinus'' plants, but will feed on privet, ''Aucuba japonica' ...
''
File:Haaniella dehaanii-subadult threaten female.JPG, Threat pose of the phasmid ''Haaniella dehaanii
''Haaniella dehaanii'' is a stick insect species. It is a typical representative of the subfamily Heteropteryginae. The occasionally used common name De Haan's haaniella refers to the species name.
Description
Both sexes, like all species o ...
''
File:Gottesanbeterin Abwehr.JPG, An adult female Mediterranean mantis
Mantises are an order (Mantodea) of insects that contains over 2,400 species in about 460 genera in 33 families. The largest family is the Mantidae ("mantids"). Mantises are distributed worldwide in temperate and tropical habitats. They ha ...
, ''Iris oratoria
''Iris oratoria'', known by the common name Mediterranean mantis (or less frequently iris mantis), due to humans first studying it in lands around the Mediterranean Sea, is a species of praying mantis. Its range is expanding in the Middle East, ...
'', in threat pose
File:Smerinthus ocellatus MHNT Female dos.jpg, Female eyed hawkmoth, ''Smerinthus ocellatus
''Smerinthus ocellatus'', the eyed hawk-moth, is a European moth of the family Sphingidae. The species was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''.
The eyespots are not visible in resting position, whe ...
'', mounted to show the large eyespots
File:Inachis io bottom side.jpg, Peacock butterfly, ''Aglais io
''Aglais io'', the European peacock, more commonly known simply as the peacock butterfly, is a colourful butterfly, found in Europe and temperate Asia as far east as Japan. It was formerly classified as the only member of the genus ''Inachis'' ...
'', is a cryptic leaf mimic when its wings are closed
File:Watching you watching me - geograph.org.uk - 235513.jpg, Peacock butterfly displays startling eyespots.
File:Speiredonia spectans.jpg, '' Speiredonia spectans'' resting mimicking a brooding head
File:Pseudocreobotra wahlbergii defence.jpg, '' Pseudocreobotra wahlbergii'' flashing its wings in deimatic pose
File:Gray_plate8.jpeg, A fine large "''Phasma''" illustrated by George Robert Gray
George Robert Gray FRS (8 July 1808 – 6 May 1872) was an English zoologist and author, and head of the ornithological section of the British Museum, now the Natural History Museum, in London for forty-one years. He was the younger brother o ...
in 1833, showing cryptic resting pose and dramatic wing flash
In arachnids
Both spiders and scorpions are venomous, so their threat displays can be considered generally aposematic. However, some predators such as hedgehog
A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found throughout parts of Europe, Asia, and Africa, and in New Zealand by introducti ...
s and spider-hunting wasps (Pompilidae
Wasps in the family Pompilidae are commonly called spider wasps, spider-hunting wasps, or pompilid wasps. The family is cosmopolitan, with some 5,000 species in six subfamilies. Nearly all species are solitary (with the exception of some group-ne ...
) actively hunt arachnids, overcoming their defences, so when a hedgehog is startled by, for instance, the sounds made by a scorpion, there is reason to describe the display as deimatic.[Edwards, 1974. pp. 158–159]
Spider
Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s make use of a variety of different threat displays. Some such as '' Argiope'' and ''Pholcus
''Pholcus'' is a genus of spiders in the family Pholcidae, with 361 described species as of October 2021.
It includes the cellar spider '' P. phalangioides'', often called the "daddy longlegs". This may cause confusion because the name "daddy ...
'' make themselves and their webs vibrate rapidly when they are disturbed; this blurs their outline and perhaps makes them look larger, as well as more difficult to locate precisely for an attack. Mygalomorphae
The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to the ...
spiders such as tarantula
Tarantulas comprise a group of large and often hairy spiders of the family Theraphosidae. , 1,040 species have been identified, with 156 genera. The term "tarantula" is usually used to describe members of the family Theraphosidae, although ...
s exhibit deimatic behaviour; when threatened, the spider rears back with its front legs and pedipalp
Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") and ...
s spread and fangs bared. Some species, such as the dangerous Indian ornamental tree spider (''Poecilotheria regalis
''Poecilotheria regalis'' is a species of arboreal tarantula and is found in parts of India. The common name for this spider is Indian ornamental tree spider, or simply Indian ornamental. It is one of the most popular arboreal tarantulas for amat ...
'') have bright colouring on the front legs and mouthparts which are shown off in its threat display when it "rears up on its hind legs, and brandishes the fore limbs and palpi in the air".
Scorpion
Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, and are easily recognized by a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always end ...
s perform non-bluffing threat displays, as they have powerful defences, but various predators still eat them. When provoked, they spread their pincers and in some cases raise their abdomens, their tails standing near-erect with the sting ready for immediate use. Some scorpions in addition produce deimatic noises by stridulating with the pedipalps and first legs.[
File:Tarantula, Attacking Position, Photo by Sascha Grabow.jpg, Aposematic threat display of Brazilian tarantula
File:Female Poecilotheria regalis, ventral shot.jpg, Belly of the spider '']Poecilotheria regalis
''Poecilotheria regalis'' is a species of arboreal tarantula and is found in parts of India. The common name for this spider is Indian ornamental tree spider, or simply Indian ornamental. It is one of the most popular arboreal tarantulas for amat ...
''. The bright yellow forelegs are used in deimatic displays.
File:Skorsh.jpg, Scorpion's threat display with pincers spread wide, abdomen raised to present sting.
In cephalopods
Deimatic behaviour is found in cephalopods including the common cuttlefish ''Sepia officinalis #REDIRECT Common cuttlefish #REDIRECT Common cuttlefish #REDIRECT Common cuttlefish {{redirect category shell, {{R from other capitalisation{{R from move ... {{redirect category shell, {{R from other capitalisation{{R from move ... {{redire ...
''). Deimatic cephalopod displays involve suddenly creating bold stripes, often reinforced by stretching out the animal's arms, fins or web to make it look as big and threatening as possible.
For example, in the common cuttlefish the display consists of flattening the body, making the skin pale, showing a pair of eyespots on the mantle, dark eye rings, and a dark line on the fins, and dilating the pupils of the eyes.