As the air heats up, tarantulas gain speed but lose coordination in their joints, researchers report April 1 in the Journal of Experimental Biology.
Tarantula legs bend and flex based on hydraulics. Bloodlike fluid called hemolymph flows into the joint to straighten and flows out to flex. Using high-speed video, researchers examined Texas Brown tarantulas (Aphonopelma hentzi) sprinting at progressively higher temperatures: 15, 24, 31 and 40° Celsius.
The tarantulas ran a lot faster at hotter temperatures, but their leg joints became less coordinated. Their swift steps limit the time hemolymph has to flow in and out of the joint.