Full Spectrum Lighting Induces Behavioral Changes and Increases Cortisol Immunoreactivity in Captive Arachnids

Area of Science:

• Zoology
• Animal Husbandry
• Comparative Physiology

Background:

• Captive husbandry of arachnids commonly includes full spectrum illumination.
• The physiological and behavioral effects of this practice on arachnids remain uninvestigated.

Purpose of the Study:

• To investigate the effects of full spectrum illumination on arachnid behavior and hemolymph cortisol levels.
• To compare responses between King baboon spiders (Pelinobius muticus) and Indian giant scorpions (Heterometrus swammerdami).

Main Methods:

• Behavioral observations and hemolymph sampling were conducted on arachnids under full spectrum light versus low-level ambient light.
• Cortisol immunoreactivity in hemolymph was measured using established immunoassay techniques.

Main Results:

• Arachnids spent significantly more time hidden under full spectrum light compared to ambient light.
• A decrease in the variety of behaviors and postures was observed in full spectrum light for both species.
• Hemolymph cortisol levels were significantly elevated in arachnids exposed to full spectrum illumination.

Conclusions:

• This study provides the first evidence of detectable cortisol immunoreactivity in arachnid hemolymph.
• Full spectrum illumination significantly alters arachnid behavior and increases physiological stress indicators.
• Current captive husbandry practices involving full spectrum lighting may be detrimental to arachnid welfare.