Boxer crabs induce asexual reproduction of their associated sea anemones by splitting and intraspecific theft.
Crabs of the genusLybiahave the remarkable habit of holding a sea anemone in each of their claws. This partnership appears to be obligate, at least on the part of the crab. The present study focuses onLybia leptochelisfrom the Red Sea holding anemones of the genusAlicia(family Aliciidae). These anemones have not been found free living, only in association withL. leptochelis. In an attempt to understand how the crabs acquire them, we conducted a series of behavioral experiments and molecular analyses. Laboratory observations showed that the removal of one anemone from a crab induces a "splitting" behavior, whereby the crab tears the remaining anemone into two similar parts, resulting in a complete anemone in each claw after regeneration. Furthermore, when two crabs, one holding anemones and one lacking them, are confronted, the crabs fight, almost always leading to the "theft" of a complete anemone or anemone fragment by the crab without them. Following this, crabs "split" their lone anemone into two. Individuals ofAliciasp. removed from freshly collectedL. leptocheliswere used for DNA analysis. By employing AFLP (Fluorescence Amplified Fragments Length Polymorphism) it was shown that each pair of anemones from a given crab is genetically identical. Furthermore, there is genetic identity between most pairs of anemone held by different crabs, with the others showing slight genetic differences. This is a unique case in which one animal induces asexual reproduction of another, consequently also affecting its genetic diversity.
The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Yisrael
Y
Schnytzer
The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Yaniv
Y
Giman
Institute of Animal Science, Agricultural Research Organization, The Volcani Center, Rishon Lezion, Israel.
Ilan
I
Karplus
The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Yair
Y
Achituv
AFLP; Asexual reproduction; Boxer crabs; Lybia; Sea anemone; Symbiosis