These male spiders catapult at impressive speeds to flee their mates
before they get eaten

Date:
April 25, 2022
Source:
Cell Press
Summary:
After males of the orb-weaving spider Philoponella prominens mate
with a female, they quickly launch themselves away, researchers
report. Using a mechanism that hadn't been described before,
the male spiders use a joint in their first pair of legs to
immediately undertake a split-second catapult action, flinging
themselves away from their partners at impressive speeds clocked
at up to 88 centimeters per second (cm/s).



FULL STORY ========================================================================== After males of the orb-weaving spider Philoponella prominensmate with a
female, they quickly launch themselves away, researchers report on April
25 in the journal Current Biology. Using a mechanism that hadn't been
described before, the male spiders use a joint in their first pair of
legs to immediately undertake a split-second catapult action, flinging themselves away from their partners at impressive speeds clocked at up
to 88 centimeters per second (cm/ s).


==========================================================================
"We found that mating was always ended by a catapulting, which is so
fast that common cameras could not record the details clearly," says
Shichang Zhang of Hubei University in Wuhan, China.

The reason the males catapult themselves is simple: to avoid being
eaten by the female in an act of sexual cannibalism. The few males the researchers saw that didn't catapult were promptly captured, killed,
and consumed by their female partners. When the researchers prevented
males from catapulting, they met the same fate.

Zhang and colleagues made this discovery while studying sexual selection
in this spider, which lives in communal groups of up to 300 individuals
in a web complex with many individual webs within it. Of 155 successful matings, they report that 152 ended with the male catapulting. All those catapulting males survived their sexual encounters.

The three males that didn't catapult were killed. Another 30 prevented
by the researchers from catapulting also got killed and eaten by the
female. The researchers say that the findings show clearly that the
catapulting behavior is required to avoid sexual cannibalism.

With high-resolution video cameras, the researchers calculated an average
peak speed of catapulting spiders of about 65 cm/s. Speeds ranged from
about 30 cm/ s to almost 90 cm/s. They also accelerated at an average
of about 200 m/s2. As they soar through the air, the males also spin
around 175 times per second on average.

The males manage to catapult at these speeds by folding their
tibia-metatarsus joint against the female. When released, hydraulic
pressure allows for rapid expansion. The joint in question lacks extensor muscles in spiders, they explain.

"We observed that males that could not perform the catapulting were cannibalized by the female," Zhang says. "It suggests that this behavior evolved to fight against female's sexual cannibalism under strong
predation pressure of females.

"Females may use this behavior to judge the quality of a male during
mating," he adds. "If a male could not perform catapulting, then kill it,
and if a male could perform it multiple times, then accept its sperm."
In future studies, they hope to explore the role of catapulting ability
in male mating success.

This work was supported by the grants from the National Natural Science Foundation of China, the Ministry of Education AcRF grants from Singapore,
and the Slovenian Research Agency.


========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Shichang Zhang, Yangjie' Liu, Yubing Ma, Hao Wang, Yao Zhao,
Matjaž
Kuntner, Daiqin Li. Male spiders avoid sexual cannibalism with
a catapult mechanism. Current Biology, 2022; 32 (8): R354 DOI:
10.1016/ j.cub.2022.03.051 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220425121113.htm

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