SICB 2013, day 2: When predators attack! (And prey escape)

Ah, the first day of a conference, when the first talks in the day might actually get some people showing up.

I spent the morning in "When predators attack," which was about the behaviour and neuroethology of attacks and escapes. Given that conference panel diversity is an ongoing topic of conversation, this one stacked up... with room to improve, with 25% of the speakers being female.

The rundown:

Jerome Casas talked about using game theory to model pursuit and evasion between crickets and spiders, and also parasitic wasps. His team modeled the spider in computations to see the disturbances the spiders made, and it matched quite well. This means that there is a very specific sensory signature of a spied attack that the cricket can recognize, and it's nothing like anything you see in the biotic world.

But having done that for 15 years in the lab, he moved into the real world (Dupuy et al 2012). They moved their piston in the field, with all the leaf litter and noise, and I'd field electrophysiology. They got evidence that the crickets can detect the spider by the wind the spider makes. But they found that the cricket "listens to everything". They could pick up cars driving by and planes flying overhead in their physiological recordings from the cricket cerci.

Barber and Kawahara gave a very cool team talk about hawkmoths. They generate my most popoular tweet of the day: some hawkmoths are able to deter bats from attacking them by making noises at the bats... with their genitals. (Strictly speaking, it was the genital scales, but that little detail got lost in the tweet.)

Chuck Derby asked: Can prey "turn off" the senses of predators, maybe using chemicals (sensory inactivation)? He suggested for octopus ink or bioluminescent flashes, but said that there is not a lot of experimental evidence. He showed some nice experiments that show opaline from sea hares (Aplysia) will block sensory neurons, primarily by the physical actor covering them with sticky goo.

Anthony Leonardo and Stacey Combes gave two talks on dragonfly attacks, both emphasizing the dynamic visual strike the dragonflies make. Leonardo emphasized more the decisions to attach, while Combes looked at the differences in the hunting behaviour from species to species, and how they handle different prey items. Turns out that while big prey have a lot more energy, they are much herder to catch.

In between the dragonfly talks, Paolo Domenici discussed variation in escape responses. Traditionally, escape responses have been viewed as stereotyped, almost reflexive behaviours, but Domenici argued (mainly using fish examples) that variation is crucial to escapes. He also showed many fast behaviours that are almost indistinguishable from escape that make distinguishing the escape responses from other behaviours tricky.

Roy Holzman is interested in what makes a good predator, and what makes a successful strike. Many models don't take into account something like suction, where a predator can capture a prey without even touching it.

Sheila Patek (one of my science crushes) asked: what does it mean to be fast? We normally think of this as pure speed, but colloquially and in science, it's more complex. She also asked us to question our assumptions about what speed "means" in a predator-prey interaction. Patek noted that the typical hypothesis is that predators and prey species are locked in an arms race to be the fastest animals. Her preliminary data from many species showed, however, that predators that are chasing after evading prey are not the fastest animals out there.

Sheila had one of the most honest moments of the session, when she described how she had this hypothesis that mantis shrimp that spear actively swimming prey should be faster than mantis shrimp that smash unmoving prey. "I tortured my grad student Maya for six years, because I did not believe her results. So this talk is in honor of grad students being tortured by PIs." Her hypothesis was wrong. The smashers are faster (comparatively; deVries et al. 2012 JEB), even though the basic mechanics are the same.

Malcolm MacIver is looking at the similarities and differences in zebra fish and electrician in how they use vision and electroreception, respectively. Larval zebra fish have a very limited range, and you also have differences based on the morphology. Zebra fish hunt in front of them, and can switch laterally very quickly, so their prey are close and near the head. Knifefish can go backward, so their prey can be in a much wider range of space.

I also learned that the cloaca (a sort of all-in-one excretory opening) of knifefish has moved way forward compared to other animals, and sits almost under the head of the fish. This is probably related to the lengthening of the anal fin the fish use to swim.

Bill Stewart was also looking at fish, but this time, how fish detect predators. Water flow is important. An intact lateral line in larva zebrafish means it is eight times more likely to escape an attack than a fish with an ablated lateral line. This also means that they can escape in the dark, using the bow wave from the predator as a directional cue to escape.

Eve Robinson talked about predators that don't move. Sea anemones are benthic predators, but that they are relatively immobile means that their hunts, and the ability of their prey to escape, is heavily affect by local water flows. Flow increases encounter rates, but this doesn't necessarily translate into changes in capture rates. Copepod prey, for instance, land on tentacles less often under low water flow, but they stay on the tentacles for a much longer time.

Speaking of copepods, Thomas Kiørboe used copepods to make the point that all animals are both predators and prey. This can make it dangerous to eat (for a copepod!).

Copepods have three feeding strategies: ambush, crushing, and creating a feeding current. These three mechanisms are not equally efficient, and each has different predation risks due to fluid disturbance. Hovering is highly efficient, but is risky and has high energy costs.

I enjoyed this session tremendously. The one problem, though, was that it made me insanely jealous. I want to be able to use all the wonderful toys they had, so I can answer a bunch of lingering questions about escape responses in decapod crustaceans! (See my review in Brain, Behavior, and Evolution on these issues.)