Reference: Biul. Bull. 197: 26-39. (August I9Q9| Bioluminescence in the Deep-Sea Cirrate Octopod Stauroteuthis syrtensis Verrill (Mollusca: Cephalopoda) SONKE JOHNSEN 1 , ELIZABETH J. BALSER 2 , ERIN C. FISHER 1 , AND EDITH A. WIDDER 1 ' Marine Science Division, Harhor Branch Oceanographic Institution. Ft. Pierce. Florida: and 2 Department of Biology, Illinois Wesleyan University, Bloomington, Illinois Abstract. The emission of blue-green bioluminescence (A m . ix = 470 nm) was observed from sucker-like structures arranged along the length of the arms of the citrate octopod Stauroteuthis syrtensis. Individual photophores either glowed dimly and continuously or flashed on and off more brightly with a period of 1-2 seconds. Examination of the anatomy and ultrastructure of the photophores confirmed that they are modified suckers. During handling, the photo-phores were unable to attach to surfaces, suggesting that, unlike typical octopod suckers, they have no adhesive func-tion. The oral position of the photophores and the wave-length of peak emission, coupled with the animals' primary postures, suggests that bioluminescence in S. syrtensis may function as a light lure to attract prey. Introduction Bioluminescence is a common and complex characteris-tic in coleoid cephalopods. A large percentage of these animals are bioluminescent, many possessing complicated light organs utilizing lenses, reflectors, irises, interference filters, pigment screens, and shutters (Harvey, 1952: Her-ring, 1988). The diversity of the morphologies and anatom-ical distributions of cephalopod photophores is unparalleled among invertebrate phyla (Voss, 1967; Herring, 1988). However, despite this extraordinary radiation, biolumines-cence appears to be rare among octopods. Although 63 of the 100 genera of squid and cuttlefish have bioluminescent species, only 2 of the 43 genera of octopods have species confirmed to be bioluminescent the bolitaenids Japetella and Eledonella (Robison and Youn. 1981; Herring el <//., Received 16 March 1999; accepted 27 May !')'> Address tor correspondence: Dr. Sonke Johnsen, MS #33, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1049. E-mail:
[email protected] 1987; Herring, 1988). In these genera, the light organs are found only in breeding females (Robison and Young, 1981 ) and are restricted to tissues associated with the oral ring and the base of the arms (Herring et ai. 1987). In the case of citrate octopods, bioluminescence has been suggested but never confirmed (Aldred et ai, 1982, 1984; Vecchione. 1987). This study provides the first description of biolumines-cence in the cirrate octopod Stauroteuthis syrtensis. We also describe the anatomy and ultrastructure of the photophores in comparison with the morphology reported for cephalopod photophores (Herring et til.. 1987) and octopod suckers (Kier and Smith. 1990; Budelmann et ai, 1997). In addi-tion, we present a hypothesis to explain how the presence of light organs relates to the feeding behavior postulated for these animals. A preliminary account of this research has been presented by Johnsen et al. ( 1999). Materials and Methods Source and maintenance of animals Three specimens of Stauroteuthis s\rtensis were obtained during a cruise of the R.V. Edwin Link to Oceanographer Canyon (on the southern rim of Georges Bank, USA) in August and September 1997. The animals were collected at depth using the research submersible Johnson-Sea-Link out-fitted with acrylic collection cylinders (11-liter volume) with hydraulically activated, sliding lids. The three speci-mens were caught during daylight at depths of 755 m (225 m from bottom), 734 m (246 m from bottom), and 919 m (165 m from bottom) (dive numbers 2925 and 2927) and maintained for up to 2 days at 8C in water collected at depth. 26
BioStor
