Hermit crab behaviors
Hermit crabs are some of the most overlooked animals in terms of their complex behavior. They are to a certain extent gregarious, some species living in distinct groups to one another (Such as Clibanarius tricolor). As such they also show many complex behaviors, such as aggressive behaviors, which usually not extent to the level of violence.[1]
Aggressive behaviors
[edit]Aggressive behaviors for hermit crabs are quite similar to one another, with some variations present between species. It usually consists on moving or positioning the legs and the chelipeds and also known as the claw or pincer. Usually these displays are enough to avoid confrontation. Though sometimes two opposing crabs will do multiple actions, with no apparent pattern. These confrontations usually last a few seconds, though some may last a few minutes, for those especially stubborn crabs.[1]
They can also raise a leg which is sometimes referred to as an "ambulatory raise". This can happen with multiple legs such as with the first two walking legs, or both the first and second pair. This are referred to as "double ambulatory raise", and "quadruple ambulatory raise", respectively. The exact form of this movement is variable between species. In some other species there is another distinct movement, where they move their leg away and upwards from the body, while it moves forwards, this same movement continues as the limb is brought down. This movement is sometimes called an "ambulatory poke".[1]
The also use their chelipeds as a warning display, usually used in two distinct variations. The first one consists in the crab lifting its whole body (shell included), and spreading its legs, then moving its cheliped forward until the dactyl (top part of the claw) is perpendicular with the ground. This movement is usually called an "cheliped presentation" This position may be more distinct in some species, such as those in the genus Pagurus. The second variation called the "cheliped extension", is usually a purely visual movement, though it may sometimes be used to strike a crab. The chelipeds move forward and upwards, until the limb is parallel with the ground, usually used to push another crab out of the way. If a larger crab pushes a smaller one, the smaller one may be moved multiple centimeters.[1]
The crabs of the family Paguridae, have a distinct type of movement present to them. Individuals may crawl upon another's crab shell. If the size is just right the crab climbed upon may move rapidly up and down or sideways, usually causing the other crab to fall off.[1]
Shell fighting
[edit]Shell fighting is a behavior present in all hermit crabs. It is a process in which the attacker hermit crab attempts to steal the shell of the victim, using a fairly intricate process. It usually only occurs if there is no empty shell suitable for the growing hermit crab. These fights are usually between the same species, though they can also occur between two separate species.[1]
If the defending crab does not retreat to the inside of its shell, an aggressive interaction will usually take place, until the defending crab retreats, or the attacker flees. After the defenders has retreated, the attacker will usually turn the shell over multiple times, holding it with its legs. It then places its chelipeds into the shell's opening.[1]
Then the crabs start the "positioning" behavior, this consists of the attacker moving side to side, over the opening of the defender's shell. This movement usually forms a figure 8. The attacker then goes into the aptly named "rapping" behavior. The attacker holds its legs and chepelothorax stationary, while it moves its shell down on the defenders shell. It is done quite rapidly, and is usually enough to produce an audible sound. It seems like little to no contact happens directly between the two crabs.[1]
After a number of "raps", the defender may come out of its shell completely. Usually positioning itself of one of the shells. The attacker then checks the now free shell, and then changes shell rapidly. As the crab tries its new shell, it usually holds its old shell, as it may decide to come back to the old one. The defeated crab then runs to the empty shell. If the defeated crab doesn't stay close to the shells, its usually eaten.[1]
Sexual behavior
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The sexual behavior inhibited by hermit crabs varies from species to species. But they usually follow some sort of order as the following. If the female possesses any larvae from a previous mating, she moults and lets them go. Female hermit crabs are ready to mate shortly before mounting, and she may come in contact with a male. In certain species the male grabs the pre-moult female for sometimes hours. Prior to the female moulting, and usually continuing after she has moulted, the male preforms precoupulatory behaviors. This vary widely but the most common are rotating/shaking the female, and jerking the female towards the male.[1]
After some time, the female moves the chelipeds in her mouth region, signaling the male. Then they both move their bodies mostly out of their shells, and mate. Both crabs then go back inside their shells, and they may mate again. In some species the male performs post-copulatory behavior until the female has the eggs on her pleopods.[1]
Grouping behavior
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Some species such as Clibanarius tricolor, Calcinus tibicen and Pagurus miamensis are semi gregarious, showing unique behaviors in groups. While this three species all showed gregarious behavior, C. tricolor, would form the densest and bigger groups. The crabs of Clibanarius tricolor congregate during the day, and usually stay with their same respective group, day after day. At 4pm the crabs would start moving in their groups, and by 5pm they had left their congregation. The congregations usually move in one general direction, and may be close to other crabs. Though this behavior seems to be lost under controlled conditions.[1]
Though they also form a different type of grouping behavior called a vacancy chain. When the attacker manages to invade the defender shell, another hermit crab steals the attacker shell, and then another hermit crab steal the other shell, and so on. It usually ends with the defending hermit crab being left with the smallest shell.[2][3]
Remodeling shells
[edit]Land hermit crabs are known for living inside shells, though this shells are usually remodeled by previous hermit crab owners. This involves a hermit crab hollowing out the shell, making it lighter. Only small hermit crabs are able to live without the remodeled shells, most big hermit crabs which where transferred to a normal shell died. Even if they where able to survive, hollowing out a shell takes precious energy, making it undesirable to any hermit crab.[2] They achieve this remodeling by both chemically and physically carving out the interiors of their shell. This shells can of course last for generations, that why some hermit crabs are able to live in areas where snails have become local extinct.[3]
Some test edits
[edit]Here's a bare URL reference[4] and another[5]
References
[edit]- ^ a b c d e f g h i j k l Hazlett, Brian A. (1966-01-01). "Social behavior of the Paguridae and Diogenidae of Curaçao". Studies on the Fauna of Curaçao and other Caribbean Islands. 23 (1): 1–143. ISSN 0166-5189.
- ^ a b Hermit crabs socialize to evict their neighbors (en-US) (2012-10-26).
- ^ a b The Social Lives of Hermits | Natural History Magazine.
- ^ https://www.jstor.org/stable/2097103
- ^ Frey, Robert W., et al. “Tracemaking Activities of Crabs and Their Environmental Significance: The Ichnogenus Psilonichnus.” Journal of Paleontology, vol. 58, no. 2, 1984, pp. 333–50. JSTOR, http://www.jstor.org/stable/1304788. Accessed 6 Jan. 2023.