- 1.
The absolute-intensity threshold of the optokinetic response in the crab Leptograpsus variegatus was measured using a moving continuous monochromatic point source. The results are compared to the photoreceptor responses of the same animal (Doujak, 1984), to determine the photoreceptor signal for the same behavioural threshold stimuli.
- 2.
Optokinetic eye movements demonstrate that at the peak of spectral sensitivity (499 nm), the minimum intensity of light the animal can detect is 4.0 ± 1.5 × 105 photons cm−2 s−1 (mean ± S.D., N = 18) incident on the eye, which is equivalent to a photon flux of about 6 photons facet−1 s−1.
- 3.
Comparison of behavioural and electrophysiological studies shows that at the above behavioural thresholds, the retinula cells respond with a train of discrete membrane depolarizations (bumps). The mean bump rate recorded in retinula cells at the absolute-intensity threshold of the optokinetic response to a moving point source is 22 ± 5 bumps min−1 (mean ± S.D., N = 6).
- 4.
Optokinetic experiments reveal an absolute sensitivity of the crab's apposition eye to a point source that is only about 900 times less sensitive than the human eye: theoretical estimates based on quantum capture efficiency and lens size predict a much larger difference. The experimental findings provide the first definitive proof that an animal possessing a compound eye can see a star, albeit only stars of 0.5 magnitude and brighter.
In the field: an interview with Harald Wolf
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In our new Conversation, Harald Wolf talks about his fieldwork experiences working with desert ants in Tunisia to understand their navigation.
Propose a new Workshop
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Our Workshops bring together leading experts and early-career researchers from a range of scientific backgrounds. Applications are now open to propose Workshops for 2024, one of which will be held in a Global South country.
Julian Dow steps down and John Terblanche joins the JEB team
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After 15 years with the journal, Julian Dow from University of Glasgow, UK, is stepping down as a Monitoring Editor. We wish Julian all the best for the future and welcome John Terblanche, Stellenbosch University, South Africa, who is joining the team. Julian talks about his long association with The Company of Biologists and the journal and John tells us about his life and career in this News article.
The capture of crude oil droplets by filter feeders at high and low Reynolds numbers
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Researchers from the University of Montreal, Canada, reveal how tiny filter feeding barnacles and Daphnia entrap and consume minute droplets of crude oil, introducing the pollutant at the bottom of the food chain.
Patterns and processes in amphibious fish
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In their Review, Keegan Lutek, Cassandra Donatelli and Emily Standen discuss the biomechanics and neural control of terrestrial locomotion in amphibious fish. They explore how locomotor mode depends on body shape, physical constraints and phylogeny.
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