MEPS 515:275-279 (2014)  -  DOI: https://doi.org/10.3354/meps11008

ABSTRACT: The squid Idioteuthis cordiformis is consumed by several apex predators, but nothing is known of its own feeding ecology. Its anomalous size and morphology within the family Mastigoteuthidae suggest that its diet may also be unusual, but material suitable for dietary studies has not been available previously. Herein, using several opportunistically collected specimens from New Zealand waters, gut contents were examined using DNA barcoding, revealing that this species feeds upon birdbeak dogfish Deania calcea and, apparently, snapper Lutjanus sp. Stable-isotope analysis of ¹⁵N and ¹³C confirmed that D. calcea occupied a trophic level immediately below that of the squid. These data suggest that this squid may prey actively upon relatively large pelagic species; alternatively, it could be net feeding and/or scavenging. I. cordiformis has ¹⁵N signatures comparable to those of the colossal squid and higher than those of the giant squid, which could indicate a high trophic position; however, further research is needed to conclusively distinguish predation from scavenging.

KEY WORDS: Idioteuthis cordiformis · Mastigoteuthidae · New Zealand · DNA barcoding · Stable isotopes