New Zealand Glowworms Use Sticky Fishing Lines to Prey Insects

Spiders are not the only animals that produce sticky substances to trap their food. According to a new study, the larvae of a glowworm group called Arachnocampa can also secrete adhesive substances that form like long lines of tiny droplets to prey insects.

The study, entitled "Characterization of the Fishing Lines in Titiwai (=Arachnocampa luminosa Skuse, 1890) from New Zealand and Australia" published in the journal PLOS ONE, details how the glowworms adhesive secretion is different from that of spiders.

Using X-ray spectroscopy and electron microscopy, the researchers analyzed the fishing lines of glowworms found in two caves in new Zealand and determined their composition.

Results showed that the glowworm's fishing lines were "very moist, water-absorbent droplets" that is totally different from the composition of spider webs. The scientists note that this difference in composition may be due to their different environment. Spiders usually thrive in dry sites while Arachnocampa glowworms live in wetter, humid areas.

But the difference of the two does not stop there. The team also found out that the fishing lines of the glowworms are excreted from their mouthparts while spiders spin their web from their abdominal glands. Analyzing the droplet's contents, they also discovered that these adhesive contains the glowworms's urine.

"Characterization of the adhesive threads of the world-renowned glowworm from New Zealand display a complete different prey capture system to those found in spiders or other glue-producing animals," said Janek von Byern from the Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Austria via Science Daily.

"These bioadhesives display a unique composition contain mainly water, hygroscopic salts, and to a very low extent also biomolecules as proteins and lipids," he added.