All-
Don't know if anyone's interested in feeding behavior of scorpions but just thought I'd post the following observations in regards to errant foraging by adult males of Euscorpius hadzii, and the ability of these small scorpions to capture large prey.
Euscorpius spp., like all other scorpions are typically placed within that nebulous classification category of sit-and-wait, generalist predators that sit in the entrances of retreats or in close proximity to a retreat entrance and wait for prey to move within capture distance.
However, errant foraging (hunting for prey away from a retreat) has been noted in scorpions and in this instance, in 2 sexually mature males of Euscorpius hadzii (small male = 31.5 mm; large male = 46 mm). Both specimens are wild-caught and from the same population.
Adult males of E. hadzii possess large, heavily-built chelae and large, elongate, laterally compressed, sub-rectangular vesicle and short, curved aculeus. The large, heavy chelae and enlarged vesicle of the telson are indicators of sexual maturity of males.
Both males are maintained in a common enclosure (2.5 gallon/9.5 L glass vivarium), with a 2"/5 cm layer of moist tan peat and multiple pieces of varying size grey slate and small, curved pieces of cork bark. This species does not seem to excavate burrows but simply adopts spaces under existing surface structure (e.g. rocks).
In the wild and in captivity, multiple specimens are often found sharing common spaces under surface structure.
In captivity, specimens are stereotypical sit-and-wait predators but on 3 occasions, adult male specimens have been observed hunting away from retreats and structure.
Errant foraging typically involves the scorpion exiting a retreat and moving randomly about an enclosure. When moving prey is detected by a scorpion, the scorpion will typically cease movement and extend the pedipalps slightly outward (laterally) and forward from the body in the direction of the moving prey. If the movement of the prey does not bring the prey into contact with the scorpion, the scorpion may advance toward the movement (vibratory signal) of the prey with pedipalps extended toward the prey or may continue waiting for 3-11 minutes before moving (searching).
When prey is encountered or contacts the scorpion, the scorpion immediately attempts to grab the prey with the chelae and restrain the prey. After several minutes, the prey is brought near to the chelicerae before being articulated in the chelae until the head is situated near to the chelicerae.
Observations of 2 feedings by the small male and 3 feedings by the large male, involved no use of envenomation to subdue and paralyze prey. Chelal capture w/o sting-use has also been observed in 2 sexually mature females of Euscorpius flavicaudis and 3 sexually mature females of Euscorpius italicus.
In 3 observed feedings (1 by small male/2 by large male) feeding began by the scorpion using the chelicerae to sever the head from the cricket. The head of each cricket fell upon the substrate and the scorpions began to feed upon the thoracic section of the cricket's body.
In one feeding involving the small male (31.5 mm in total length), I introduced an adult female cricket (A. domesticus - 27 mm in total body length). The small male was outside the retreat and when the cricket made contact with the male during movements around the enclosure, the male immediately attacked and captured the cricket with the chelae. Despite the struggles of the cricket, the cricket was brought head first toward the chelicerae of the scorpion, which began feeding on the head. After 4 minutes, 22 seconds, the scorpion released the cricket from the chelae and carried it with the chelicerae around the enclosure for almost 2 minutes before moving beneath a piece of cork bark, where it resumed feeding - in a position of negative geotaxis (upside down) without any signs of difficulty in retaining the cricket in this position.
It was quite remarkable to see this small scorpion attack, capture and restrain prey almost as large as its total body length without the use of venom.
Luc
Don't know if anyone's interested in feeding behavior of scorpions but just thought I'd post the following observations in regards to errant foraging by adult males of Euscorpius hadzii, and the ability of these small scorpions to capture large prey.
Euscorpius spp., like all other scorpions are typically placed within that nebulous classification category of sit-and-wait, generalist predators that sit in the entrances of retreats or in close proximity to a retreat entrance and wait for prey to move within capture distance.
However, errant foraging (hunting for prey away from a retreat) has been noted in scorpions and in this instance, in 2 sexually mature males of Euscorpius hadzii (small male = 31.5 mm; large male = 46 mm). Both specimens are wild-caught and from the same population.
Adult males of E. hadzii possess large, heavily-built chelae and large, elongate, laterally compressed, sub-rectangular vesicle and short, curved aculeus. The large, heavy chelae and enlarged vesicle of the telson are indicators of sexual maturity of males.
Both males are maintained in a common enclosure (2.5 gallon/9.5 L glass vivarium), with a 2"/5 cm layer of moist tan peat and multiple pieces of varying size grey slate and small, curved pieces of cork bark. This species does not seem to excavate burrows but simply adopts spaces under existing surface structure (e.g. rocks).
In the wild and in captivity, multiple specimens are often found sharing common spaces under surface structure.
In captivity, specimens are stereotypical sit-and-wait predators but on 3 occasions, adult male specimens have been observed hunting away from retreats and structure.
Errant foraging typically involves the scorpion exiting a retreat and moving randomly about an enclosure. When moving prey is detected by a scorpion, the scorpion will typically cease movement and extend the pedipalps slightly outward (laterally) and forward from the body in the direction of the moving prey. If the movement of the prey does not bring the prey into contact with the scorpion, the scorpion may advance toward the movement (vibratory signal) of the prey with pedipalps extended toward the prey or may continue waiting for 3-11 minutes before moving (searching).
When prey is encountered or contacts the scorpion, the scorpion immediately attempts to grab the prey with the chelae and restrain the prey. After several minutes, the prey is brought near to the chelicerae before being articulated in the chelae until the head is situated near to the chelicerae.
Observations of 2 feedings by the small male and 3 feedings by the large male, involved no use of envenomation to subdue and paralyze prey. Chelal capture w/o sting-use has also been observed in 2 sexually mature females of Euscorpius flavicaudis and 3 sexually mature females of Euscorpius italicus.
In 3 observed feedings (1 by small male/2 by large male) feeding began by the scorpion using the chelicerae to sever the head from the cricket. The head of each cricket fell upon the substrate and the scorpions began to feed upon the thoracic section of the cricket's body.
In one feeding involving the small male (31.5 mm in total length), I introduced an adult female cricket (A. domesticus - 27 mm in total body length). The small male was outside the retreat and when the cricket made contact with the male during movements around the enclosure, the male immediately attacked and captured the cricket with the chelae. Despite the struggles of the cricket, the cricket was brought head first toward the chelicerae of the scorpion, which began feeding on the head. After 4 minutes, 22 seconds, the scorpion released the cricket from the chelae and carried it with the chelicerae around the enclosure for almost 2 minutes before moving beneath a piece of cork bark, where it resumed feeding - in a position of negative geotaxis (upside down) without any signs of difficulty in retaining the cricket in this position.
It was quite remarkable to see this small scorpion attack, capture and restrain prey almost as large as its total body length without the use of venom.
Luc
