DEEP-SEA PAGES:
MESOPELAGIC (MIDWATER) ANIMALS

MESOPELAGIC (and some BATHYPELAGIC) ANIMALS

Pelagic animals are those that live in the open water, not closely associated with the seafloor. Benthic (bottom-associated) animals are found on most of my other animal webpages (use the menu, upper right).

A. DEEP PELAGIC FISHES -- Oregon/NE Pacific

Midwater trawl Lanternfish accidentally caught with Alvin (2006) and Viperfish caught with midwater trawl during Alvin expedition (2007)

These are fish that we caught either as our deep-sea bottom otter trawl rose, or by our midwater trawl (figure, left top). Most are MESOPELAGIC (about 200-1000m), but some of these species are also found in the deeper BATHYPELAGIC zone (below 1000m) and ABYSSOPELAGIC (below about 3000m, but poorly defined). The deepest known fish is at about 8300m (see Bathyal and Abyssal Fishes page). Other pictures below were obtained from submersibles. Animals here--fishes, jellyfish, shrimp, etc.--must adapt to low food supplies. They eat each other, and/or the detritus falling down from above. Some species are vertical migrators--they migrate to the upper waters at night to eat where there is more food. Animals have very low protein contents and relatively weak muscles (our research found 5-10% protein in most deepsea fish species' muscles, compared to 15-20% for epipelagic fish like tunas). Many species also have elaborate mechanisms for catching food because it is so infrequent: devices such as huge teeth, and expandable jaws and stomachs that allow them to swallow prey larger than themselves. They also often have special adaptations to cope with low light levels, such as large eyes and photophores (light-producing organs)--about 75% of mesopelagic organisms are bioluminescent. See the UCSB Bioluminescence or the Harbor Branch Oceanographic Bioluminescence page for more information on biological light production. Thanks to Ruben Pohl for the depth ranges, which are listed first as peak abundance, followed by record depths. TO FIND almost any FISH SPECIES in the world, go to FISHBASE. The Taiwan Fishbase site (mostly non-English) has many pictures of fishes from all depths, and can be searched by fish family names (in English). MORE DETAILS on DEEP SEA FISH can be found at Jeff Drazen's U. Hawai'i site

Crested Bigscale Poromitra crassiceps (Primary depth 300-3200m)	Daggertooth Anotopterus pharao/nikparini ( 500-2700m; young rise to 20m ?)	Barreleye Macropinna microstoma ( mainly 500-1000m)	Barreleye, top view	Snipe eel Nemichthys scolopaceus (mainly 50-1500m)	Hatchetfish (see NOTE below)
Headlightfish Diaphus theta ( 0-200 at night; 300-1000 during day; max 1687m?)	Northern Pearleye Benthalbella dentata ( mainly 400-1000m)	Dragonfish Tactostoma macropus ( 50-200m at night; 300-1600m during day; max 2000m?)	Fangtooth Anoplogaster cornuta (mainly 300-2000m; larvae 0-200m)	Anglerfish
Viperfish Chauliodus macouni ( mainly 250-950m; max 4231m?)	Another viperfish Note light organ behind eye	Ventral light organs on viper and lanternfish	. Viper/Dragonfish gape	.. Stout Blacksmelt and "gel" layer Pseudobathylagus (Bathylagus) milleri (200-1400m; max. 6600m !) --see note below--

Our Research: In the 1980s we found that some midwater fish have buoyant gelatinous layers (ABOVE RIGHT: layer just under skin in the blacksmelt cross-section). They also have very low protein content in muscles. These are probably adaptations to an energy-poor environment; it also means these are not very good for human consumption. Our publications on midwater fish anatomy and biochemistry: --Siebenaller, J.F., P.H. Yancey (1984). The protein composition of white skeletal muscle from mesopelagic fishes having different water and protein contents. Mar. Biol. 78: 129-137 --Yancey, P.H., R. Lawrence-Berrey, M. D. Douglas (1989). Adaptations in mesopelagic fishes. I. Buoyant glycosaminoglycan layers in species without diel vertical migrations. Mar. Biol. 103: 453-459 --Yancey, P.H., T. Kulongoski, M.D. Usibelli, R. Lawrence-Berrey, A. Pedersen (1992). Adaptations in mesopelagic fishes. II. Protein contents of various muscles and actomyosin contents and structure of swimming muscle. Comp. Biochem. Physiol. 103B: 691-697

MORE INFORMATION: Bigscales have large scales often lost during capture. Eaten by diving mammals and larger fish. Barreleyes and Blacksmelts are some of the few fish known to eat gelatinous midwater animals such as salps(below). One report places this blacksmelt down to 6600m, in the abyssopelagic. Barreleyes have their huge eyes permanently focused to look straight up. Snipe Eels use their elongated jaws to catch shrimp, perhaps by entangling shrimp antennae. Headlight- and other Lantern-fish are found in all oceans, and have photophores all along their ventral (belly) sides, and some have headlight ones on their heads. They migrate up to the surface at night then down during the day. Pearleyes have tubular eyes directed up as well as forward. Dragonfish have no scales, have ventral and sometimes near-eye photophores. Anglerfish have a glowing lure (often shaped like an animal) dangling on a fin ray over their huge jaws. See Animal Pictures Archives and Ramkat's site for great pictures. Hatchetfish: these fish have ventral (belly) light organs, possibly to provide illumination that blends them in with the weak light from above ("counterillumination"). They are also very narrow (laterally compressed) like a knife blade, which also makes them hard to see by a predator looking up into the light. I don't have a good picture, but Animal Pictures Archives and Monterey Bay Aquarium do. Viperfish have a hinged skull, allowing the skull to rotate up for swallowing large prey. They also have large stomachs. They have various light organs, including one on a long dorsal fin that serves as a lure. From submerisbles they have been seen hanging motionless with their lure over their mouths, waiting for prey (see Randall and Farrell book above). Gulper Eels (not shown) have huge mouths and jaws to swallow almost anything. See the Monterey Bay Aquarium's photo and information

Dragonfish Astronesthes martinii (depth 350-1500m) from the Red Sea; photos provided by Ruben Pohl of Vienna, Austria:

B. OTHER DEEP PELAGIC ANIMALS--Oregon, California/NE Pacific

Most of these images are crude ones from a submersible video camera, except for the octopods caught by trawl .
**CLICK PICTURES FOR LARGE VERSIONS**

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Gelatinous zooplankton--Salps, larvaceans, siphonophores; 250-880m deep. Most are Larvacea (taken from submersible camera). I took the leftmost-one with Alvin's video at 880m.	Unknown--rear (left) tentacles were moving	Jelly or hydrozoan medusa* at 511m	Teuthowenia-type squid (seen from Alvin at 880m)	Cirrate octopods. See MOLLUSC PAGE for details

C. DEEP PELAGIC ANIMALS--NEW ZEALAND: PETER BATSON'S Photos **These great pictures are not mine, but are copyrighted and courtesy of PETER BATSON , marine researcher and author of DEEP NEW ZEALAND-Blue Water, Black Abyss (2003). Please do NOT use the pictures without his permission! See his website: Exploretheabyss.com.

**CLICK PICTURES FOR LARGE VERSIONS**

Teuthowenia, an odd midwater squid			Ever- manella	Argyropelecus	Astronesthes	Bathysaurus	Hydrolagus, a chimaera (relative of sharks)

A nice overview of common and interesting deepsea animals (with some of my pictures) can be found at Sea and Sky. The Monterey Bay Aquarium Deepsea page has excellent pictures	Pictures and descriptions of the strange bathypelagic Anglerfish are at Ramkat's website. For pictures and information on the giant oarfish, click here
	A nice site with drawings and animations of deep pelagic animals (vampire squids, anglerfish, etc.) can be found at CYBERSPACE: Below the EDGE. The Monterey Bay Aquarium Deepsea page has excellent pictures of real pelagic animals in their habitats, including Gulper Eels, jellies, ctenophores, etc..
	Pictures of the bizarre midwater Vampire squid can be found at Smithsonian Magazine.
	See the UCSB Bioluminescence or the Harbor Branch Oceanographic Bioluminescence page for more information on biological light production, including in the deep sea.

HOME PAGE: CONTENTS, ZONES

1. Bacteria; Unknowns; WORMS

2. BATHYAL and ABYSSAL FISHES

3. ECHINODERMS

4. CNIDARIA, Porifera

5. MOLLUSCS, CRUSTACEA, PYCNOGONIDA

7. SURFACE (EPIPELAGIC)

8. METHANE SEEPS and VENTS