Hammerhead sharks (Sphyrnidae) are have a large amount of morpholigcal variation within the family, making them the focus of many studies. The size of the laterally expanded head, or cephalofoil, is inversely correlated with pectoral fin area. The inverse relation in cephalofoil and pectoral fin size in this family suggests that they might serve a complimentary role in lift generation. The cephalofoil is also hypothesized to increase olfaction, electroreception, and vision; however, little is known about how morphological variation impacts post-cranial swimming kinematics. Previous studies demonstrate that the bonnethead and scalloped hammerhead have significantly different yaw amplitude and we hypothesized that these species utilize varied frequency and amplitude of undulation along the body. We analyzed video of free swimming sharks to examine kinematics and 2D morphological variables of the bonnethead and scalloped hammerhead. We also examined the second moment of area along the length of the body and over a size range of animals to determine if there were shape differences along the body of these species and if those changed over ontogeny. We found that both species swim with the same standardized velocity and Strouhal number but there was no correlation between two-dimensional morphology and swimming kinematics. However, the bonnethead has a dorso-ventrally compressed anterior trunk and undulates with greater amplitude whereas the scalloped hammerhead has a laterally compressed anterior trunk and undulates with lower amplitude. We propose that differences in cross-sectional trunk morphology account for interspecific differences in undulatory amplitude. We also found that for both species, undulatory frequency is significantly greater in the anterior body compared to all other body regions. We hypothesize that the bonnethead and scalloped hammerhead swim with a double oscillation system.
2023 JEB Outstanding Paper Prize shortlist and winner
The JEB Editors are delighted to announce the shortlisted authors for the 2023 JEB Outstanding Paper Prize. Read the winning paper - Tiny spies: mosquito antennae are sensitive sensors for eavesdropping on frog calls - by Hoover Pantoja-Sanchez and Brian Leavell from Ximena Bernal's lab at Purdue University, USA.
JEB Science Communication Workshop for ECRs
If you’re an early-career researcher interested in science communication and are attending the SEB Annual Conference in Prague this summer, come a day early and join the JEB Editors at a sci comm workshop to learn the key writing skills needed to promote your research to a broad audience beyond your peers (1 July at 14.30-17.30). Places are limited to 24 attendees, and applicants should apply through the SEB registration page by 30 April 2024.
Bridging the gap between controlled conditions and natural habitats in understanding behaviour
Novel technologies enable behavioural experiments with non-model species, in naturalistic habitats and with underexplored behaviours. In their Commentary, Scholz and colleagues discuss how to obtain a deeper understanding of the natural ecology and lifestyle of study animals.
How a macrourid fish remains buoyant at depths it should be unable to reach
Fish with swimbladders should not be capable of descending below 7200m, but when Alan Jamieson and Todd Bond spotted a macrourid fish at 7259m, they knew they had seen something miraculous. Working with Imantes Priede, they reveal that the swimbladder of a 1 kg fish could hold 37.9 g of oxygen, sufficient to offset the weight of the fish's bones, and take 221-440 days to fill, which is plausible because it takes years for the fish to descend to such depths.
ECR Workshop on Positive Peer Review
Are you an ECR looking for tips on how to write concise, astute and useful manuscript reviews? If so, join the JEB Editors at a 2-hour JEB-sponsored Workshop on Positive Peer Review at the Canadian Society of Zoologists annual meeting in Moncton on 9 May 2024 at 13.00-15.00. There are 25 spaces for ECRs and selection is first come, first serve. To sign up, check the ECR Workshop box when you register for the CSZ meeting.
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