Growth and claw regeneration of the stone crab, Menippe mercenaria

Savage, T. and J.R. Sullivan. 1978. Growth and Claw Regeneration of the Stone Crab, Menippe mercenaria. Fla. Mar. Res. Publ. No. 32.23 pp. Laboratory-maintained and feral crabs were observed for incremental carapace width and major and minor claw growth. Morphometric relationships for male and female carapace width against length and carapace width against major and minor claw sizes were derived. Only slopes of carapace width us. female major and male minor claws were not significantly different at the 95% confidence level. Feral normal male incremental growth exceeded that of normal females for all parameters. Normal laboratory females possessed greater average carapace width growth but less claw growth than did their male counterparts. All laboratory growth was more uniform but incrementally smaller than corresponding field growth. A hypothetical growth plot constructed from incremental growth of several crabs indicated ages at attainment of sexual maturity and legal size to be 10 and 30 months. A pictorial description of stone crab claw regeneration is presented. Minor claws realized greater regeneration after one and two molts (73.5% and 96.5% of pre-autotomized sizes) than did major claws (68.6% and 89.0%). Intermolt interval of laboratory crabs increased with larger carapace width sizes. Claw loss shortened or lengthened duration of the intermolt period depending upon whether the claw was removed shortly after a molt or later in the cycle. (Document has 27 pages.

Prediction of discard mortality for Alaskan crabs after exposure to freezing temperatures, based on a reflex impairment index

Millions of crabs are sorted and discarded in freezing conditions each year in Alaskan fisheries for Tanner crab (Chionoecetes bairdi) and snow crab (C. opilio). However, cold exposures vary widely over the fishing season and among different vessels, and mortalities are difficult to estimate. A shipboard experiment was conducted to determine whether simple behavioral observations can be used to evaluate crab condition after low-temperature exposures. Crabs were systematically subjected to cold in seven different exposure treatments. They were then tested for righting behavior and six different ref lex actions and held to monitor mortality. Crabs lost limbs, showed ref lex impairment, and died in direct proportion to increases in cold exposure. Righting behavior was a poor predictor of mortality, whereas reflex impairment (scored as the sum of reflex actions that were lost) was an excellent predictor. This composite index could be measured quickly and easily in hand, and logistic regression revealed that the relationship between reflex impairment and mortality correctly predicted 80.0% of the mortality and survival for C. bairdi, and 79.4% for C. opilio. These relationships provide substantial improvements over earlier approaches to mortality estimation and were independent of crab size and exposure temperature

Catching crabs: a case study in local-scale English conservation

Wells-next-the-Sea and Cromer in Norfolk (England) both rely upon their local crab populations, since crabbing (gillying) is a major part of their tourist industry. Compared to a control site with no crabbing, crabs from Wells harbour and Cromer pier were found to have nearly six times the amount of limb damage. Crabs caught by the general public had more injuries than crabs caught in controlled conditions, suggesting the buckets in which the crabs were kept were to blame. Since there is much evidence that such injuries have negative impacts on the survival and reproductive success of the shore crab, this is taken as evidence of non-lethal injury from humans having a population-level effect on these animals. Questionnaire data demonstrated a public lack of awareness and want for information, which was then used to obtain funding to produce a leaflet campaign informing the public of how to crab responsibly. All data collected is available online at http://dx.doi.org/10.6084/m9.figshare.979288

Eumeces laticeps

Number of Pages: 3Integrative BiologyGeological Science

Evolution of antipredator behavior in an island lizard species, Podarcis erhardii (Reptilia: Lacertidae): The sum of all fears?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110598/1/evo12555.pd

Evidence of tail autotomy in the European plethodontid Hydromantes (Atylodes) genei (Temmick and Schlegel, 1838) (Amphibia: Urodela: Plethodontidae)

7 páginas, 1 figura.Caudal autotomy is a defensive mechanism widely adopted by lungless salamanders (Plethodontidae) from the New World. In contrast, in Europe, this mechanism was not described until very recently for just one Sardinian species, Hydromantes (Speleomantes) sarrabusensis. We report on tail autotomy observed in another species from the same island, Hydromantes (Atylodes) genei. In Europe, self-amputation of the tail seems to be restricted to some plethodontids inhabiting Sardinia, while continental species do not exhibit analogous antipredator strategies.This study was supported by grant CGL2009-11663 from the Minsterio de Ciencia e Innovación and grant 2009 SGR 1462 from the Generalita de Catalunya to SC.Peer reviewe