AsianScientist (Jun. 9, 2016) – When male fiddler crabs look for a mate, they vibrate their claws. This unique mating ritual helps the females decipher the size and stamina of their suitors, according to a study published in The Science of Nature.
During mating season, the males of some fiddler crab species construct a raised mound or semi-dome near their burrows. They stay close to their burrows and wave their one distinctively large claw to attract females to their burrow’s entrance. Once a female comes closer, the male repeatedly emits vibrations to lure her even further into his hideout, with the intention to eventually mate.
Study authors Drs. Fumio Takeshita of Nagasaki University and Minoru Murai from the University of the Ryukyus went to the tidal flat of Nagaura Island in Kumamoto, Japan to investigate how these vibrations might be helping female fiddler crabs (Uca lactea) to decide on a preferred mate. The researchers used a female dummy to elicit courtship vibrations from several males, which they then recorded and analyzed.
The researchers learned that these acoustic signals consist of repetitive pulses. The lower the dominant frequency, the more likely the male crab was large. The length of the pulses decreased slightly when more vibrations were repeatedly produced. The interval between such pulses also increased when more pulses were produced.
“These factors imply that the vibrations convey information on male characteristics, such as body size and stamina,” said Takeshita.
Observing fiddler crabs mating with real females, the researchers also looked at what happened once the females were successfully lured to a burrow entrance. Females were more likely to enter the burrow of males that waved their claws higher and for a longer period of time.
“This indicates that the females use the male vibrational signals to decide whether to enter the burrow or not,” added Murai.
Once a female finds herself inside a burrow, the continuous production of vibrations plays no further role in her decision to mate, the researchers found. Instead, aspects such as the protective structure of the burrow, in which she will possibly release larvae, might then come into play.
The article can be found at: Takeshita & Murai (2016) The Vibrational Signals that Male Fiddler Crabs (Uca lactea) Use to Attract Females into Their Burrows.
———
Source: Springer; Photo: Fumio Takeshita.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
