Encyclopaedia of Cryptozoology
Pallid sailfin

The pallid sailfin drawn by Else Bostelmann for Beebe, who reported seeing solitary specimens.

Classification Osteichthyes
Proposed scientific names Bathyembryx istiophasma (Beebe, 1934)
Other names
Sea reported Atlantic Ocean
First reported 1934[1]
Prominent investigators William Beebe

The pallid sailfin (Bathyembryx istiophasma) was a cryptid deep sea fish seen twice, off Bermuda in the Atlantic Ocean, during a bathysphere dive by William Beebe on 11 August 1934.[2][3][4] Beebe classified it as an aberrant genus of flabby whalefish (family Cetomimidae).[1]


According to Beebe, who could not make out all anatomical details during the sightings, the pallid sailfin was rather large for a deep sea fish, at least 2 ft (0.6 m) in length, somewhat elongated in shape, tapering slowly towards the tail. The tail itself was almost absent, "reduced to a tiny knob or button," but had comparatively large, vertical, sail-like fins above and below, "lengthening rapidly in a concave curve high above and far below the body ... posteriorly they were truncated...". Its mouth was wide, and it possessed long pectoral fins, "apparently rather soft, if not filamentous, broad, and abruptly rounded at the tips." Its colour was described as "sickly," "an unpleasant pale, olive drab, the hue of water-soaked flesh, an unhealthy buff," and it showed no bioluminescence whatsoever. The fish did not seem to notice either the bathysphere or its electric light.[1][4]



From 1930 to 1934, Beebe and his colleague Otis Barton (1899 – 1992), based on Nonsuch Island in Bermuda, performed several pioneering deep sea dives in a bathysphere, an unpowered submersible designed by Barton. These record-setting dives allowed them to observe deep sea life alive for the first time. During a descent on 11 August 1934, at a depth of 1,500 ft (457 m), Beebe observed his first pallid sailfin after turning on an electric light at the starboard window.[1][4] Beebe was in constant telephone communication with his colleague Gloria Hollister (1900 – 1988) during the dives, and described the pallid sailfin to her as he watched it.[4]

Pale flesh-colored fish around 2 feet long, no lights. It is a pale pasty whitish-buff and very high melanostomiatic fins. Grand clear view, memorized details.

Beebe later described what he had memorised in more detail in his formal description of Bathyembryx istiophasma and in his book Half Mile Down (1934), both written in the same year as the sighting.[4]

Finally, without my seeing how it got there, a large fish swung suspended, half in, half out of the beam. It was poised with only a slow waving of fins. I saw it was something wholly unknown ... But all this time I sat absorbing the fish from head to tail through the wordless, short-circuiting of sight, later to be materialized into spoken and written words, and finally into a painting dictated by what I had seen through the clear quartz.
The strange fish was at least two feet in length, wholly without lights or luminosity, with a small eye and good-sized mouth. Later, when it shifted a little backwards I saw a long, rather wide, but evidently filamentous pectoral fin. The two most unusual things were first, the color, which, in the light, was an unpleasant pale, olive drab, the hue of water-soaked flesh, an unhealthy buff. It was a color worthy of these black depths, like the sickly sprouts of plants in a cellar. Another strange thing was its almost tailless condition, the caudal fin being reduced to a tiny knob or button, while the vertical fins, taking its place, rose high above and stretched far beneath the body, these fins also being colorless. I missed its pelvic fins and its teeth, if it had any, while such things as nostrils and ray counts were, of course, out of the question...
Although I had already seen many deep-sea forms on this dive, yet here was one larger than any we had ever taken in nets. The Sailfin was alive, quiet, watching our strange machine, apparently oblivious that the hinder half of its body was bathed in a strange luminosity. Preeminently, however, it typified the justification of the money, time, trouble, and worry devoted to bringing the bathysphere to its present efficiency ... With no visible increase of fin vibration, my Pallid Sailfin moved into outer darkness, and when I had finished telephoning the last details I ordered a further descent. This entire volume would not contain the detailed recital of even a fraction of all the impressive sights and forms I saw, and nothing at these depths can be spoken of without superlatives.

Further down on the same dive, while suspended for some time at a depth of 2,500 ft (762 m), Beebe again saw what he believed to be a pallid sailfin, making this the only one of his abyssal fishes to be seen on multiple occasions. His verbal report to Hollister stated "flesh-colored one back again but can't see outline."[4]

The sight I enjoyed most was a momentary glimpse of what I am certain was the same, or another, Pallid Sailfin. In all this vast extent in three dimensions, of black water, the chance of confirming at a wholly different depth a new observation made my satisfaction complete.


Beebe classified the pallid sailfin as a possible genus of cetomimid fish (Public Domain).

In his formal description of Bathyembryx istiophasma, Beebe argued that it likely belonged in or near the family Cetomimidae, the flabby whalefishes, "although it is a very distinct form."[1] The flabby whalefishes, which exhibit extreme sexual dimorphism, are some of the deepest-living fish known. During the observation itself, he had described the fish's tailfins as "melanostomiatic," dragonfish-esque.[4]

Five deep-sea fishes were described by Beebe on the basis of his bathysphere observations: the pallid sailfin, giant dragonfish (Bathysphaera intacta), three-starred anglerfish (Bathyceratias trilynchus), and five-lined constellationfish (Bathysidus pentagrammus), alongside the scientifically-undescribed abyssal rainbow gar. Beebe was wary of describing new species without extensive study of the animal's anatomy and behaviour, but, knowing there would be no second chances to describe the fishes he saw during his dives, he chose to assign taxonomic names to some of the most memorable and distinctive of them, with verification from Barton.[5] The "type specimens" of these abyssal fishes were drawings made by Else Bostelmann under Beebe's supervision, showing only characteristics of which he was certain.[4] Due to the circumstances of the observations, the lack of physical holotypes, and the absence of any later sightings, Beebe has been accused of misinterpreting or inventing his abyssal fishes,[6] although Bathyembryx istiophasma continues to appear on taxonomic lists.

Notes and references[]

  1. 1.0 1.1 1.2 1.3 1.4 Beebe, William "Three New Deep-Sea Fish Seen From the Bathysphere," Bulletin of the New York Zoological Society, Vol. 37, No. 6 (1934)
  2. Eberhart, George M. (2002) Mysterious Creatures: A Guide to Cryptozoology, ABC-CLIO, Inc., ISBN 1576072835
  3. Shuker, Karl P. N. "A Supplement to Dr Bernard Heuvelmans' Checklist of Cryptozoological Animals," Fortean Studies, Vol. 5 (1998)
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Beebe, William (1934) Half Mile DownOnline
  5. Gould, Carol Grant (2012) The Remarkable Life of William Beebe: Explorer and Naturalist
  6. Ballard, Robert D. & Hively, Will (2017) The Eternal Darkness: A Personal History of Deep-Sea Exploration