By Phil Eyden
Note: Phil welcomes discussion on this article in the Cephalopod Fossils forum.
One of the most interesting, popular, and intriguing of all living cephalopods is that of Vampyroteuthis, the Vampire Squid. To follow is a brief look at this 'living fossil', its history, behaviour and lifestyle.
Vampyroteuthis was first discovered and described in 1903 by the German marine biologist Dr Carl Chun, who served aboard the research ship Valdavia, then engaged in deep-sea surveys off the Guinea Basin in the Atlantic Ocean, during which the first specimen was trawled at a depth of 1,400 meters. So taken by the bizarre appearance of this animal, Chun named it Vampyroteuthis infernalis, literally the 'Vampire Squid from Hell', owing to its dark-red skin, purplish-black web, fins, white beak and deep-set red eyes -- giving it a somewhat nightmarish appearance. He described it as a somewhat gelatinous, small-finned octopus that he believed to be fairly inactive.
The next forty-or-so
years saw numerous Vampyroteuthis collected from the Atlantic, Pacific
and Indian Oceans, with specimens attributed to no less than eleven species in
eight genera. Following detailed
analyses, Dr Grace Pickford (1946) concluded that all of these forms were
likely ontogenetic stages of a single species and that only one valid genus and
species existed, V. infernalis.
A LIVING FOSSIL?
In order to appreciate the significance of Vampyroteuthis, we need to go back in time to a truly ancient period, the early Carboniferous. Due to the lack of fossils, our understanding of early coleoid (i.e. squid, octopus, cuttlefish and belemnoid) evolution is rather poor, but it seems clear that approximately 350 million years ago the earliest internally shelled coleoid cephalopods began to appear in the oceans, living alongside the nautiloids and the earliest ammonoids. Despite large gaps in the fossil record of early coleoids it appears that this important leap in cephalopod evolution took place rapidly, given the near instantaneous appearance of the earliest ancestors of many modern coleoid groups.
From a common externally shelled nautiloid ancestor today's familiar cephalopod lineages began to take their different paths. The belemnoids, with their ten equal arms beset with hooks and internal shell, taking one path, only to become extinct 65 million years ago. The decapod lineage, eventually leading to modern squid and cuttlefish, reduced the internal shell further, and developed two feeding tentacles from the basic ten-armed bauplan. Octopods evolved at least 300 million years ago and slowly lost an arm pair altogether, leaving them with eight arms only. The earliest vampyromorph is thought to have appeared at about the same time, probably sharing an ancestor with the earliest octopods, although it is also possible that octopods are derived from primitive vampyromorphs. (See Fig. below)
Although thought to lack close relatives in today's oceans, Vampyroteuthis has numerous extinct relatives, most aligned to it on grounds of distinctive gladius morphology -- usually the only part of the animal to fossilise. This distinctive transparent vampyromorph gladius extends the length of the mantle, is broad in shape, thin in profile, has lateral wing-like extensions and a small non-chambered terminal conus.
Vampyromorphs appeared during the Carboniferous and evolved to become a moderately diverse group by the Jurassic, only to spread world by the Late Cretaceous. Their fossilised remains are relatively common in the Jurassic Solnhofen limestone deposits in Germany and the Cretaceous limestones from Lebanon. Some species attained giant size, such as the Late Cretaceous Tusoteuthis - a beast similar in size to the modern giant Architeuthis - and others developed a peculiar long, tapering gladius - such as Plesioteuthis, a common form known from the Late Jurassic in Germany.
One of the most interesting fossil relatives of Vampyroteuthis, Provampyroteuthis giganteus, was described in 1998, discovered amongst stomach contents of an 86 million year old elasmosaurid plesiosaur found at Hokkaido, Japan. Between the plesiosaur's ribs and gastroliths were numerous black-wedge shapes attributed to the upper and lower jaws of a vampyromorph, the upper half bearing a striking resemblance to modern Vampyroteuthis infernalis, though the lower half bore a resemblance to Nautilus. However, this ancient animal was much larger, approximately three times the size of the living vampire. Furthermore, this vampyromorph must have been a coastal, shallow-water species, as plesiosaurs are thought to be shallow-water swimmers. Perhaps predation in the Cretaceous drove vampyromorphs to deeper water, further influencing their present-day bizarre morphology.
ANATOMICAL FEATURESIndeed, the Vampire Squid is a relictual cephalopod, and the sole survivor of a once large and diverse group. Naturally, being related to both octopus and squid it shares with them certain characters and character states. However, it also has its own distinct lineage that differs sufficiently from others to justify its classification in a unique Order. Some of its unique features are herein described.
Vampyroteuthis is unique amongst the cephalopods in that it has two pairs of lobed fins, although only one pair is apparent in the adult. The recently hatched juvenile has a pair of small fins located at the rear of the mantle. However, at a mantle length of approximately 15 - 25mm, the first pair is slowly absorbed back into the mantle, only to be replaced by a larger pair located slightly forward of the first. Consequently, during the time the first pair is being reabsorbed and the second pair is developing, Vampyroteuthis briefly has two pairs of fins. This remarkable feature is ancient, that is relictual; the fossil Late Jurassic vampyromorph Trachyteuthis also had two pairs of fins, although in this genus they would appear to have persisted throughout the adult life. It is possible that the earliest vampyromorphs, and possibly early octopods too, evolved with two pairs of fins.
Most systematic confusion can be attributed to researchers attributing various ontogenetic stages of this animal to different species, especially juvenile forms, given the variable number and position of fins and their relative sizes.
Vampyroteuthis has two large light organs located at the base of the fins at the rear of the animal. These large circular photophores have shutters that the animal can use to turn the light on and off as well as vary the intensity of the emission. These organs likely serve to dissuade or disorient potential predators, as they resemble disproportionately large, glowing eyes. Additional light organs are situated on the tips and length of the arms, and beneath the head and body; none is present on or within the web. In theory, these light-emitting organs adjust the intensity of light emitted over various surfaces of the body, depending on the animal's orientation in the water column at any point in time. As light penetrating from above would not pass through the animal's dense body tissues, a black silhouette (apparent shadow) would be apparent to any prospective predator approaching from below. By emitting light at a comparable intensity to that penetrating from above, the light organs render the animal effectively invisible; the process is called counter-illumination. These animals also have a remarkable third source of bioluminescence, in that they can produce a cloud of luminescent particles embedded in mucus from their arm tips, serving to distract potential predators. These 'glowing clouds' can persist for up to ten minutes; they are a unique feature of Vampyroteuthis (no other cephalopod has this ability).
As with the finned cirrate octopods, and most incirrate deep-water octopods Vampyroteuthis lacks an ink sac. Such a feature would be largely redundant for a creature that lives in the abyss. Similarly, chromatophores are very poorly developed, as the ability to change colour rapidly is quite redundant in the deep sea. Whatever chromatophores this species has are reddish interspersed with black, and they are incapable of changing size or shape.
The Vampire has two further unique structures present in no other extant cephalopod - two long filaments housed in pits between the first arm pair. These filaments are capable of being extended (and retracted) for hunting purposes. They are probably vestiges of Arm Pair II, thought by some researchers to be the same arms that octopods lost when departing from the 10-armed ancestral bauplan (implying a close relationship between these two groups), although others believe that these filaments may be related to the tentacles of Nautilus. Normally rolled up inside pits between the vampyromorphs first and second arms, when deployed they can sense disturbances in the surrounding water, enabling the Vampire to both evade predators or seize prey; on a fully mature adult, when fully extended these filaments can reach a meter in length.
The arms have a single row of suckers, although these commence within the web, starting about half-way along the arms, and extend to the arm tips. Either side of these suckers, extending the length of the arm, they also have a row of projections (cirri) that are believed to aid detection of prey (by functioning as sensory receptors), and possibly assist in manoeuvring prey toward the beaks. The arms are connected by a deep web, also believed to aid in prey capture. If bitten off by a predator the arms are capable of regenerating.
LIFESTYLE AND BEHAVIOUR
If all specimens of Vampyroteuthis now represented in collections truly belong to a single species then V. infernalis is very widely distributed, having been recorded from tropical and temperate waters of the Atlantic, Pacific and Indian Oceans. Pickford recorded most of her specimens were taken from waters between 2.0° and 5.9°C and salinities of 34.70‰ to 34.99‰. It generally lives at a depth of 600 - 900m (though specimens have been captured between 5001500m) and tends to inhabit the oxygen minimum zone (OMZ), where practically no other cephalopods live. Despite the fact that it has the lowest metabolic rate of any cephalopod yet studied, it is extremely efficient in processing these low levels of oxygen; levels as low as 3% have been recorded from the Vampire's local environment. The animal has particularly large gills to draw oxygen and its blue blood contains very efficient respiratory proteins, i.e. haemocyanins, to bind and transport oxygen. It maintains buoyancy via the use of statoliths (balancing organs akin to a human's inner ear) and tissues rich in ammonium ions that closely match the density of surrounding seawaters.
Surprisingly, for a small, poorly muscled and gelatinous animal, Vampyroteuthis is an effective swimmer, at least over short distances. As an adult the fins provide the major locomotory thrust - the muscle groups powering them being the largest in the body - although it is still capable of conventional jet propulsion. The juvenile, with under-developed fins, is probably more reliant on conventional jet propulsion. To conserve energy the Vampire tends to remain fairly inert, drifting in the water column, orientated horizontally, with its filaments deployed to sense prey; upon prey detection the Vampire moves swiftly towards it using its fins to envelop the prey within its web-shaped bell. When threatened or disturbed the Vampire beats a hasty retreat by combined use of finned flight and jet propulsion; it is capable of moving up to two body lengths per second and making rapid turns, although it is incapable of sustained swimming or flight-response activity as it lacks the stamina.
As red light does not penetrate into the ocean depths where the Vampire lives, its dark-red colour renders it practically invisible to potential predators. If stressed the animal can draw its web over its head and mantle creating the impression of an unappetising spiny ball, this is known as the 'pumpkin' or 'pineapple' posture. It is believed that the array of defensive features mentioned above, i.e. bioluminescence, glowing ejecta and ability to draw the web over the mantle, are all predator-avoidance adaptations to conserve energy rather than engage in sustained flight.
Analysis of stomach contents indicates that the animal feeds on small jellyfish, copepods, prawns, diatoms and other planktonic animals. In turn, it is predated upon by pinnipeds, some benthopelagic fishes and number of whales, including the Sperm Whale, Pygmy and Dwarf Sperm Whales, and the Northern Bottlenosed Whale.
The male Vampyroteuthis
impregnates the female using its penis which is concealed within its funnel.
During mating the male transfers packets of sperm, spermatophores, to receptive
ducts located below each of her eyes, where they are stored for extended
periods of time before she using them to fertilise her eggs. It is believed that the female produces a
small egg mass in her oviducts, where eggs can be kept for long periods of
time, possibly as long as a year (one of the major anatomical distinctions
between vampyromorphs and cirrate octopods is that vampyromorphs retain both
oviducts, whereas cirrate octopus have only a single oviduct). The fertilised
eggs are then discharged into the water in small clusters (in cirrate octopuses
the eggs are anchored to the seabed).
To finish with a fun fact, the vampire squid actually has the largest eye of any animal relative to body size. A fully grown female can have an eye that is an inch across, comparable to a fully grown dog. For this it will shortly earn itself a place in the Guinness Book of Records!
Brad Seibel (CEPHBASE)
Kim Fulton-Bennett (MBARI)
Steve Haddock (MBARI)
Mike Everhart (Oceans of Kansas)
REFERENCES, LINKS AND FURTHER READING:Bolstad, K. 2003
Deep-Sea Cephalopods: An Introduction and Overview
D. T. Donovan, L. A. Doguzhaeva, H. Mutvei. 2003
Two pairs of fins in the Late Jurassic Coleoid Trachyteuthis from Southern Germany
Haddock, S.H.D.; McDougall, C.M.; Case, J.F.
"The Bioluminescence Web Page",
Johnson, B. 2000.
"Vampyroteuthis infernalis" (On-line), Animal Diversity Web.
Bruce H. Robison, Kim R. Reisenbichler, James C. Hunt and Steven H. D. Haddock, 2003.
Light Production by the Arm Tips of the Deep-Sea Cephalopod Vampyroteuthis infernalis
Full Text: http://www.biolbull.org/cgi/reprint/205/2/102
MBARI link with images of bioluminescence: http://www.mbari.org/midwater/vamp/
BA Seibel, EV Thuesen and JJ Childress, 1998.
Flight of the vampire: onto genetic gait-transition in Vampyroteuthis infernalis (Cephalopoda: vampyromorpha)
Full Text: http://jeb.biologists.org/cgi/reprint/201/16/2413
Tree of life pages on Vampyroteuthis (Richard Young):
COPYRIGHTAll photographs are the property of the copyright owners as indicated in the pictures. Please do not duplicate them without written permission from the owners. This does not apply to Chun's Vampire Squid engraving which is over 100 years old and is in the public domain, and my own family tree diagram.
Phil Eyden - Nov 2005
Vampyroteuthis Infernalis, Living Fossil
By Phil Eyden