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Sceloporus jarrovi (Yarrow's Spiny Lizard). Ocular sinus bleeding.
... In that context, it is worth noting that Sceloporus jarrovii and Urosaurus ornatus have been reported to ooze blood during lassoing captures. This was attributed to ocular-sinus autohemorrhaging (Mahrt, 1996;Sherbrooke, 2000). Sherbrooke (2000) suggested that ocular-sinus bleeding during such cranially associated tactile trauma during predator attacks may have been an event(s) that led to the evolution of a blood-squirting defense in Phrynosoma carrying blood chemicals distasteful to some predators. ...
... This was attributed to ocular-sinus autohemorrhaging (Mahrt, 1996;Sherbrooke, 2000). Sherbrooke (2000) suggested that ocular-sinus bleeding during such cranially associated tactile trauma during predator attacks may have been an event(s) that led to the evolution of a blood-squirting defense in Phrynosoma carrying blood chemicals distasteful to some predators. ...
... Apparently, not all species of horned lizards squirt blood in response to predators Hodges, 2004;Sherbrooke and Mendoza-Quijano, 2005). The blood-squirting mechanism, based on bloodflow control in the head (Bruner, 1907;Heath, 1966), and its evolution have been discussed (Sherbrooke, 2000;. The targeted mammalian-sensory receptors of the chemical constituents of squirted blood have not been studied previously. ...
Investigamos la hipótesis de que el lanzamiento de un chorro de sangre por los senos orbitales por los camaleones texanos (Phrynosoma cornutum), es una defensa antidepredatoria contra algunas especies mamíferas. Coyotes (Canis latrans) fueron probados por primera vez. Como era de esperarse, los camaleones arrojaron sangre en respuesta a los ataques de los coyotes, y los coyotes se mostraron sorprendidos, las evitaron, o hicieron ambos como resultado de los eventos. Mientras que los cadáveres de las lagartijas mezcladas con alimento típico provocaron vómito en los coyotes, posiblemente debido a efectos físicos, la sangre de camaleones mezclada con la comida no lo produjo. Las respuestas de los coyotes a lanzamientos simulados de 5 compuestos, incluyendo sangre de camaleones, hacia 3 áreas potencialmente sensitivas del coyote (ojos, nariz y boca), sugieren fuertemente que los efectos de rechazo fueron provocados por receptores en cavidades orales o nasales. Respuestas de coyotes fueron más frecuentes con lanzamiento de plasma sanguíneo y sangre entera de Phrynosoma a las membranas nasales y orales que con lanzamiento de plasma y sangre provenientes de lagartijas espinosas (Sceloporus jarrovii), o con lanzamiento de un control salino en esas membranas. Concluimos que los camaleones arrojan chorros de sangre por los senos que rodean sus ojos durante ataques de caninos, como coyotes, y que esta sangre afecta los receptores orales, causando una respuesta negativa en el comportamiento del ataque del coyote que probablemente incrementa la supervivencia de las lagartijas.
Autohemorrhaging behavior in Cuban dwarf boas, genus Tropidophis (Serpentes: Tropidophiidae) Autohemorragia en majasitos cubanos del género Tropidophis (Serpentes: Tropidophiidae) Many anti-predation strategies have been described among reptiles. Autohemorrhaging is a less common mechanism that consists of the voluntary expulsion of blood through the cloaca or mouth. It has been repeatedly documented in dwarf boas of the genus Tropidophis. Herein we describe the occurrence of this phenomenon for the first time in three Cuban dwarf boas (Tropidophis celiae, T. hendersoni and T. wrighti), and two new reports for T. melanurus, all endemic. The events reported here confirm that such behavior mostly occurs under stressful conditions. Anti-predation strategy, autohemorrage, snake, stressful conditions. Numerosas estrategias anti-depredación se han descrito entre los reptiles. La autohemorragia es un mecanismo poco común que consiste en la expulsión voluntaria de sangre a través de la cloaca o la boca. Se ha reportado en reiteradas ocasiones en las boas enanas del género Tropidophis. En este trabajo describimos la ocurrencia de este fenómeno por primera vez para tres majasitos cubanos (Tropidophis celiae, T. hendersoni y T. wrighti) y dos reportes nuevos para T. melanurus, todos endémicos. Los eventos aquí reportados confirman que dicha conducta principalmente ocurre bajo condiciones estresantes. Autohemorragia, condiciones estresantes, estrategia antidepredación, serpiente.
Variability within the genus Phrynosoma in the occurrence of ocular-sinus blood-squirting, reportedly a defense used in canid encounters, is reviewed from the literature. Six species have been reported to squirt blood, and seven species remain unreported. Five of the latter species were tested in dog trials; one exhibited blood-squirting (Phrynosoma hernandesi), one exhibited precursor behaviors but failed to squirt blood (Phrynosoma ditmarsi), and three yielded negative results (Phrynosoma mcallii, Phrynosoma modestum, and Phrynosoma platyrhinos). Instances of blood-squirting in response to human encounters were collected and largely support the negative results for the three species P. mcallii, P. modestum, and P. platyrhinos. A phylogeny of blood-squirting and nonblood-squirting species is presented with blood-squirting being plesiomorphic in the genus and the synapomorphic condition of nonsquirting species being restricted to a single clade of P. mcallii-modestum-platyrhinos. The possibility of P. douglasii independently evolving an autapomorphic condition remains unresolved. Dog trials with 40 adult Phrynosoma cornutum were conducted to determine influences of body size and sex on squirt frequency and blood mass expelled, as well as to examine aspects of the potential physiological cost of the defense. In 153 trials, 85% of all lizards squirted in at least one trial, 82% squirted in more than one trial, and two lizards squirted daily over the seven-day trial period. Initial body mass positively correlated with the total number of squirts/individual (r2 = 0.28; P < 0.001) and the number of days a lizard continued squirting (r2 = 0.63; P < 0.01). Number of squirts/individual/day declined over the seven-day trial period (r2 = 0.20; P < 0.05). Cumulative mass loss for individual lizards attributable to blood-squirting averaged 0.7 ± 0.8 g (2.0 ± 2.0% body mass), with a high of 2.8 g (6.8% body mass). In addition, juvenile P. cornutum and P. hernandesi were shown to squirt blood in dog trials, illustrating the early developmental onset of the behavior.
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