Vampyroteuthis infernalis

Vampyroteuthis infernalis

Vampyroteuthis infernalis, the vampire squid from hell, is a cephalopod that lives in the oxygen minimum layer (600 - 800 m depth) throughout the world's temperate and tropical oceans. V. infernalis is the only cephalopod that lives its entire life cycle in the core of the oxygen minimum layer (OML). Oxygen minimum layers are pelagic habitats with continously low oxygen levels at midwater depths (400 - 1000 meters, depending on location) over vast areas. OML's greatly influence species distributions throughout the world. In contrast to other low oxygen habitats (i.e. tidal pools), OML's are stable over very long periods of time (1000's of years). Oxygen levels in the OML in some regions are less than 5% of air saturation (0.25 ml O2/l). Pickford (1936) coined the term "oligoaerobic" (oligo = a few; aerobic = oxygen) to describe V. infernalis' restriction to low oxygen habitats. Most cephalopods are unable to withstand oxygen levels below about 50% of air saturation and only a few, such as Nautilus, can tolerate oxygen as low as 20% (Seibel et al., 1999; Wells and Wells, 1995). V. infernalis accomplishes its extraordinary tolerance of low oxygen by being especially effective at removing oxygen from the water. It has a hemocyanin (respiratory blood pigment) that binds oxygen extremely effectively (Seibel et al., 1999). In conjunction with its very low metabolic rate and relatively high gill surface areas (Madan and Wells, 1995; Seibel and Childress, 1996), V. infernalis' high affinity hemocyanin allows it to carry out its routine functions without the use of anaerobic metabolism.

The vampire squid has much in common with both squids and octopuses but it was placed in its own Order, the Vampyromorpha, based on the presence of sensory filaments. These filaments are believed to be used for finding food in the dark deep sea (Hunt, 1996). The vampire squid deploys its filaments one at a time, drifting for several moments after deployment. If a prey animal makes contact with the filament, the vampire squid swims in a sweeping arc to the point where contact was made in hopes of catching the intruder. The filaments were originally believed to be modified arms. However, a careful anatomical study has shown that the filaments are innervated very differently than are the arms, suggesting that they are uniquely derived (Young, 1967).

Another unique aspect of the biology of Vampyroteuthis infernalis is the dramatic metamorphosis that results in changes in the size, shape and position of the fins. At about 15 - 25 mm mantle length, juvenile V. infernalis begin grow a second set of fins located more anteriorly (toward the arms) than the first pair. Once the new pair reaches a functional size, the original pair is reabsorbed. This transition reflects a change in gait (swimming style), from jet propulsion as juveniles, to aquatic 'flight' using fins as adults (Seibel et al., 1998). The metamorphosis confused early cephalopod researchers who described several "species" of vampire squid until Grace Pickford (1936; 1949; 1952) was able to determine that the two-finned 'species' was actually a juvenile stage of the one-finned 'species'. Today there is only one recognized species in the order Vampyromorpha.

Vampyroteuthis infernalis is named for its jet-black skin (although their color varies from black to red to purple and seems to depend on the light conditions), the caped appearance of the webbing between the arms, and eyes that appear red under some light conditions (the eyes appear blue when viewed from a submersible). William Beebe (1926) described V. infernalis as "a very small but terrible octopus, black as night with ivory white jaws and blood red eyes". Despite this horrific description, V. infernalis is a rather docile animal, and most often hangs motionless in the water column, with only slight movements of the fins for balance. Dr. Richard Young (1964) wrote that V. infernalis "has no more control over its location in the water column than that exercised by the common jellyfish". V. infernalis does, in fact, have the lowest metabolic rate of any cephalopod ever measured (Seibel et al., 1997).

However, recent observations from submersibles (Hunt, 1996) and physiological measurements (Seibel et al., 1998) have shown that, despite its weak musculature, V. infernalis is capable of fairly rapid swimming using fins for underwater 'flight'. This form of swimming is similar to that used by penguins, sea turtles, sea lions, pteropods (sea butterflies) and many fishes. The statocysts (balance organ, analogous to the human inner ear) of V. infernalis suggest that they are capable of fair agility (Stephens and Young, 1976). Although it can move rapidly for short distances, the physiology of V. infernalis suggests that it is not capable of the long migrations and the extended fight and flight responses that shallow-living squids endure (Seibel et al., 1997; 1998). A variety of bioluminescent displays (Herring et al., 1994; Hunt, 1996) combined with unpredictable flips and turns allow V. infernalis to hide safely from pursuing predators in its darkened habitat without swimming more than a few meters.

Studies using remotely operated vehicles at the Monterey Bay Aquarium Research Institute have revealed remarkable predator avoidance displays. Light organs on the tip of each arm and at the base of each fin begin to glow and pulse and the arms begin to writhe. It becomes very difficult to tell one end of the vampire squid from the other. Then, V. infernalis ejects a mucus containing thousands of "glowing spheres of blue bioluminescent light" (Hunt, 1996). When the light show ends, it is difficult to tell if the black vampire squid has flown away in the dark, and if so, in which direction, or if it has merely faded into the lightless waters around it.


Also see Introducing Vampyroteuthis by Richard Ellis.

References and Credits

Credits

Text and photograph by Brad Seibel, a Postdoctoral Research Fellow at UM and expert on Vampyroteuthis.

References

Beebe, W. (1935). Half Mile Down, pp. London: John Lane The Bodley Head.

Herring, P. J., Dilly, P. N. and Cope, C. (1994). The bioluminescent organs of the deep- sea cephalopod Vampyroteuthis infernalis (Cephalopoda: Vampyromorpha). J. Zool., Lond. 223, 45 - 55.

Hunt, J. 1996. The behavior and ecology of midwater cephalopods from Monterey Bay: submersible and laboratory observations. Ph.D. Dissertation.

Hunt, J. C. (1996). Octopus and Squid, 64 pp. Monterey Bay Aquarium Foundation.

Madan, J. J. and Wells, M. J. (1996). Why squid can breathe easy. Nature 380, 590.

Pickford, G. E. (1939). The Vampyromorpha. A new order of dibranchiata Cephalopoda. Vestnik Cs. Zool. Spol. Praze VI, 346-358.

Pickford, G. E. (1946). Vampyroteuthis infernalis Chun, an archaid dibranchiate cephalopod: natural history and distribution. 29.

Pickford, G. E. (1949). Vampyroteuthis infernalis Chun an archaid dibranchiate cephalopod: external anatomy. 32, 132.

Pickford, G. E. (1952). The Vampyromorpha of the Discovery expeditions. XXVI, 197-210.

Seibel, B. A., Chausson, F., Lallier, F. H., Zal, F. and Childress, J. J. (1999). Vampire blood: respiratory physiology of the vampire squid (Cephalopoda: Vampyromorpha) in relation to the oxygen minimum layer. Exp. Biol. Online 4.

Seibel, B. A. and Childress, J. J. (1996). Deep-breathing cephalopods. Nature.

Seibel, B. A., Thuesen, E. V. and Childress, J. J. (1998). Flight of the Vampire: Ontogenetic gait-transition in Vampyroteuthis infernalis (Cephalopoda: Vampyromorpha). J. exp. Biol. 201, 2413-2424.

Seibel, B. A., Thuesen, E. V., Childress, J. J. and Gorodezky, L. A. (1997). Decline in pelagic cephalopod metabolism with habitat depth reflects differences in locomotory efficiency. Biological Bulletin 192, 262-278.

Stephens, P. R. and Young, J. Z. (1976). The statocyst of Vampyroteuthis infernalis (Mollusca: Cephalopoda). J. Zool., Lond. 180, 565-588.

Wells, M. J. and Wells, J. (1995). The control of ventilatory and cardiac responses to changes in ambient oxygen tension and oxygen demand in Octopus. J. Exp. Biol. 198, 1717-1727.

Young, R. E. 1964. The anatomy of the Vampire Squid. University of Southern California.

Young, R. E. (1967). Homology of retractile filaments of vampire squid. Science 156, 1633-1634.

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