This extremely large scyphozoan is known from relatively few specimens collected by research submersibles and trawls. Several partial specimens were collected from a wide range of locations in the 1960s, from the Gulf of Mexico to the Indian Ocean to the Southern Ocean. It has been reported in the literature only occasionally since. Generally found in water several hundred to 2600m deep, and difficult to collect intact due to its size, anatomical descriptions of this animal are based on incomplete specimens and photographs and observations made through the windows of collecting submersibles. (Russel, 1967)
Deepstaria enigmatica is unusual among jellyfish in possessing a distinct, highly branched canal system distributed uniformly over the bell and resembling wire netting. This network is the animal's digestive tract, and is characteristic of the genus. Deepstaria enigmatica was the first species named in its genus, and was named in honor of the vessel which collected it, the research submersible Deepstar. (Russel, 1967)
The species returned to public attention in April 2012 with a sighting at an unnamed location, captured in a video circulated on the internet. The sighting was confirmed to genus level by researchers at the Monterey Bay Aquarium Research Institute who promptly published a video describing the natural history of Deepstaria.
"During Dive 159 of the U.S. research submersible Deepstar 4000 on 22 October 1966 Dr Eric G. Barham, Dr George Pickwell, and Mr Ronald Church collected a remarkable scyphomedusan at a depth of about 723 m in the San Diego Trough. The specimen was collected by means of a suction device. In a letter to me Dr Barham said ' when first noted, the jellyfish's margin was collapsed and the exumbrella indented. As we maneuvered to bring the medusa in a position with the intake funnel of the collecting device, the vortex of the craft swirled the umbrella open. It was fully a metre in greatest dimensions '. 'Because of its size, not all of the specimen could fit into the pump container, and we returned to the surface with part of it still extending from the funnel.' Four of the photographs taken at the time are reproduced in Pl. I.
Dr Barham most kindly sent me the specimen for examination. He and his colleagues are to be congratulated on bringing this distinctive medusa successfully to the surface.
The medusa is incomplete. Most of the umbrella margin is missing as well as the central stomach region. All that came into the collecting device is however saved, including some portions of gonad and tissue with gastric cirri which had broken away from the body. Examination of the underwater photographs indicates that the medusa was in fact incomplete before it was caught. It was probably in a moribund state and was incapable of normal pulsation. The umbrella could be seen in some photographs to be distorted and twisted about by the turbulence caused by the Deepstar submersible. It appeared to be very tenuous and flexible.
In its preserved state the umbrella is obviously much contracted and probably compressed by the collecting apparatus. When spread out subumbrellar surface upwards it measured about 50 cm in diameter (Pl. II, fig. t). On opposite sides of the umbrella are two large tubular shaped processes. Dr Barham said that these were caused by bubbles of air which stretched the mesogloea. The umbrella has the form of a deep bell whose apex is missing. The mesogloea is solid and rather tough, but uniformly thin, being everywhere about 1-2 cm in thickness. It is much contracted and thrown into puckers and folds. It has a yellowish brown tinge and contains many mesogloeal cells. No epithelium is present. The mesogloea may have already been disintegrating and is of a floppy texture.
The radial canal system is most striking. It consists of a meshwork, likened by Dr Barham to wire-netting. The meshes are elongated radially and the whole system leads outwards to the umbrella margin. A portion of the umbrella showing the canal network is reproduced natural size in Pl. II, fig. 2. The whole network appears to be uniformly distributed over the umbrella and I could find no indications of any major straight canals leading from the centre to the periphery. The stomach portion of the umbrella is missing, but the network of canals can be seen to originate in the centre of the umbrella in a number of single straight canals of varying thickness which presumably connect with the stomach cavity.
In places around the margin there are portions of a narrow coronal muscle. Two such pieces can be seen in Pl. I, fig. 2, and they are also to be seen in Pl. II, fig. These portions of the margin are much contracted by the muscle and they gather the umbrella into little puckers. In its contracted state the muscle is about 15 mm in width.
The canal system at the margin in the region of the coronal muscle ends in a fine network of canals having the appearance shown in Text-fig. 1A. The meshes are compressed in a concertina-like fashion. A piece of stretched and mounted margin is shown in Text-fig. 1B. It is evident that there are complete but small meshes but it is not possible to decide whether they lead into a single ring canal. It is also not possible to determine whether there were any marginal tentacles.
The gonads are situated along the margins of fan-shaped mesenteries, and tend to be broken up into several isolated processes with incurved edges. The specimen is a male. The outer convex side of each process has thick mesogloea and the numerous oval sperm follicles are situated on the inner concave side embedded in the mesogloea (Text-fig. 2A). Each follicle is about 0.15— 0.25 mm in diameter and sections show spermatocytes and spermatozoa (Text-fig. 2 B).
Only one gonad was still attached to the umbrella. This was cut away for examination and photographing. It is shown natural size in Pl. III. The single straight canals which issue from the canal network in the central region can be seen running towards the base of the gonad mesentery. Some of these canals appear to be continued over the mesentery to the gonad tissue.
Three other gonads were found broken away. These had at the bases of their fan-shaped mesenteries an area of fragile tissue covered with many gastric cirri, possibly the subumbrella wall of the stomach. Where the fan-shaped gonadial mesentery narrows at its base it is continued into a grooved piece of solid mesogloea the sides of which have gastric cirri along them for a short distance. This solid mesogloea is continued as an elongated trough reminiscent of the axial groove of an oral arm. I am unable in fact to decipher what this could be. If it continued into the oral arm the gonads would be perradial, a position unknown in Scyphomedusae. In Text-fig. 3 I have drawn diagrammatically a gonad with this mesogloeal appendage and one is shown nearly natural size in Pl. IV. We know from the gonad shown in Pl. III that it is attached to the subumbrella. I have tried to suggest the situation in an inset sketch in Text-fig. 3, but until an intact specimen is obtained it is not possible to reconstruct the whole animal. Three of the appendages can be seen in Pl. I, fig. 4.
The gastric cirri had many nematocysts (Text-fig. 2c), but I could find none discharged. They were all of one kind, microbasic euryteles, 20-25 nm long and 8-11 nm wide. The gastric cirri were full of fat globules.
Until a more complete specimen of this medusa is obtained it is not possible to place it either in the Semaeostomeae or the Rhizostomeae, and its systematic position must remain uncertain. For this reason I name it Deepstaria enigmatica gen.nov., sp.nov., in recognition of its capture by Deepstar and its uncertain systematic position.
It is sufficient at this stage to regard the remarkable uniform network of the gastro-vascular canal system as a generic character. Such a canal system is not found in any known species of Scyphomedusae. It bears a resemblance, however, to the canal system of the ‘abnormal’ young medusae found in the viviparous species Stygiomedusa fabulosa (Russell, 1959; Russell & Rees, 1960, p. 313, Pl. IV), but it is perhaps stretching matters too far to suggest that this new species might be the sexual stage of the viviparous form.
The specimen had a large isopod in it, whose position is indicated in Pl. I, fig. I."
(Russell, 1967)
Deepstaria enigmatica is a very rarely seen giant jellyfish of the family Ulmaridae first described in 1967 by F. S. Russell.
The Deepstaria enigmatica has a wide, thin bell (up to 60 cm or 2 ft),[1] transparent in appearance, which undulates as the jellyfish moves. They are usually found in Antarctic and near-Antarctic seas, but have been spotted in waters near the United Kingdom and Gulf of Mexico, at depths of 600–1,750 metres (1,970–5,740 ft).[1][2] Unlike many other jellyfish, they lack tentacles.[3] They also are solitary creatures, contrary to the group living style of many jellyfish.
The large bell of the jellyfish has been proposed as used for either locomotion or feeding when closed. The gastrovascular system of the jellyfish can be clearly seen through its skin.[3] The Deepstaria also features a geometric mesh pattern throughout its entire body; this mesh delivers nutrients to the entire jelly as it stretches and contracts to move and capture prey.[4]
Members of Deepstaria have a thin, umbrella-like membrane, a gastrovascular cavity, and lack tentacles. Deepstaria enigmatica move by peristalsis. This is done through contractions that travel in wave-like motion throughout its body. They have no tentacles, and instead use the peristaltic wave as means of locomotion and capturing prey.[4] The jellyfish begin these wave-like contractions by opening the mouth of the bell as a wave travels through their body. A bulge forms in the center of the body and remains as long as the mouth of the bell remains closed.[4]
Deepstaria enigmatica have been observed during jelly-falls. This happens when a jellyfish carcass falls through the water column to the ocean floor. A Deepstaria enigmatica jelly fall was first observed in the lower portion of the oxygen minimum zone of the ocean. It was observed as shrimp and crabs were scavenging its carcass.[4]
These jelly falls are advantageous to the ocean floor, causing a source of organic enrichment, similar to a whale fall; as carcasses decay away from light and the more oxygen-rich environments of the upper ocean, the animal decays far slower, providing a longer-lasting source of nutrients. The carcasses lead to a restoration of degraded mineral content in the water column. The contribution of these jelly falls is underestimated. The Deepstaria enigmatica fall shows an increase in oxygen availability and organic matter, benefitting the ecosystems found at the bottom of the ocean.[4]
Deepstaria open and close their bell, or stomach cavity, allowing them to both move and take in prey. This motion also allows isopods (a member of the crustacean family) to enter and live inside the jellyfish. Although the nature of this relationship is not fully understood, scientists currently believe that the isopod rides along and gains nutrients from the Deepstaria while being protected from predators. When the isopod and Deepstaria were seen together in a 1967 dive, scientists reported that the isopod was bright red, around 8 cm (3.1 in) in length, and appeared active, suggesting some form of beneficial symbiotic relationship. This dive and other findings were recorded in a 1969 article by E.G. Barham and G.V. Pickwell. Their paper identifies the isopod as member of the genus Anuropus. The authors also suggest the possibility of the symbiotic relationship being parasitic.[5][6]
The Deepstaria jellyfish, unlike many jellyfish, lacks tentacles of any kind, which other species of jellyfish commonly use to entrap and consume prey. Instead, Deepstaria trap prey inside their bell, where they are consumed. This method also provides for isopods, who may live inside the jellyfish's bell in a symbiotic relationship.[7]
In the 1960s Jacques Cousteau, a French explorer, unexpectedly found the Deepstaria jellyfish in a deep-sea exploration mission. He was exploring the deep sea near Southwest Baker Island in a submarine called the Deepstar 4000, which became the inspiration for the name of this jellyfish. The Deepstaria jellyfish has been found in the Gulf of Mexico, Antarctic, and the Pacific Ocean. In all of these locations, the jellyfish was found 3,000 ft (910 m) below sea level.[8]
Deepstaria enigmatica is a very rarely seen giant jellyfish of the family Ulmaridae first described in 1967 by F. S. Russell.
