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Transforming water fleas prepare for battle!
Water fleas can thwart their enemies by growing defensive structures such as helmets and spines. What’s more, this predator-induced ‘arming’ process is not a one-size-fits-all approach - they can even tailor their defensive responses to the types of predators present.
How are water fleas (Daphnia) able to do this and how does it impact the ecosystems of ponds and lakes? Dr Linda Weiss at Ruhr-University Bochum, Germany, who is leading this research explains: “As they grow up and moult, juvenile Daphnia can develop formidable ‘armour’, including helmets, spines or crests, when they detect specific chemical cues in the water left by predators such as fish, phantom midge larvae and backswimmers. These defences are speculated to act like an anti-lock key system, which means that they somehow interfere with the predator’s feeding apparatus. Many freshwater fish can only eat small prey so, for example, Daphnia lumholtzi grows head and tail spines to make eating them more difficult.”
Caption:Undefended Daphnia longicephala (left) is compared with the defended phenotype (right). The defended phenotype has a large crest as well as elongated tail spines in response to chemical cues from the backswimmer Notonecta glauca. Credit: Dr Linda Weiss

(via currentsinbiology)

Source: eurekalert.org