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Next article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCoverThe Atlantic blue crab, Callinectes sapidus, occurs naturally in the western Atlantic Ocean from Nova Scotia to Argentina. A commercially important species, it is a member of the swimming crab family Portunidae. The blue crab is highly active, swimming and walking to find food, evade predators, find mates, and avoid adverse conditions such as low environmental oxygen. It is also capable of migrating over long distances. The male blue crab engages in a behavior associated with reproduction where a male courts a female and then carries her beneath him, with his walking legs wrapped around her body, for up to one week. When the female then molts, the crabs copulate and the male crab continues this “mate guarding” behavior for a time. The crab illustrated here is a female, as is evident in this view from the reddish tips of her claws.In this issue (pp. 63–67 and 68–78), authors Stover et al. report on a novel mechanical “pull force” test to measure fatigue in the walking legs used during mate guarding. Large crabs appear to have an advantage over smaller crabs as previously suggested in the literature. Blue crabs are also capable of sustaining up to six hours of continuous walking on a treadmill. Low oxygen profoundly decreases the length of time crabs are able to walk, increases the turning and stopping behaviors associated with fatigue, and reduces their performance in “pull force” tests. Interestingly, elevated carbon dioxide at moderate levels of low oxygen does not reduce performance. As zones of low oxygen and dead zones of anoxia spread worldwide, animals living in coastal marine habitats will struggle to reproduce and thrive. Blue crabs are no exception. These studies show that important behaviors associated with reproduction and locomotion in blue crabs are strongly influenced by size and oxygen availability. The authors also describe some of the biomechanical features of the walking legs during locomotion and how these features change with fatigue.Credits: Illustration © Tamara Clark, www.tamaraclark.com; cover design, Beth Liles, Marine Biological Laboratory. Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 224, Number 2April 2013 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv224n2cover Views: 233 © 2013 by Marine Biological Laboratory. All rights reserved.PDF download Crossref reports no articles citing this article.