Deep-sea fish use hydrothermal vents to incubate eggs

Date:  February 12, 2018

Source:  Penn State

Summary:

An international team of researchers have discovered egg cases of deep-sea fish near hydrothermal vents. The team believes that deep-sea skates, a relative of sharks and rays, use the warm water near the vents to accelerate the typically years-long incubation time of their eggs.

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Newfound Glow-in-the-Dark Fish Identified

By Kacey Deamer, Staff Writer | August 11, 2016 10:12am ET

With distinct tubular eyes and a natural glow, two species of bioluminescent deep-sea fish nicknamed "barreleyes" have been identified.

The newly described species are part of the family Opisthoproctidae. Barreleye fish are not well-described, due to the rareness and fragility of specimens, the researchers said.

These fish are "one of the most peculiar and unknown fish groups in the deep-sea pelagic realm, with only 19 morphologically disparate species," the scientists wrote in their new study.

However, the scientists were able to determine the two newfound species through comparisons of pigment patterns on the fish's "sole." This organ, found along the belly of some bioluminescent species, controls the light emitted from a different, internal organ. These two organs give the fish their glowing properties.

"The entire external surface of the sole is covered with large, thin scales showing gradually increasing pigmentation toward the distal parts, thereby functioning as a light screen when the reflector is contracted (no light emission) or expanded (light passes through the thin, transparent parts of the scales)," the researchers wrote in the study.

The fish scales' pigment patterns show variation among species. The researchers took four specimens of a sole-bearing barreleye caught during recent research cruises near American Samoa and New Zealand and compared them to long-preserved specimens caught near the mid-Atlantic ridge and Australia. In doing so, the scientists found three different pigment patterns, suggesting three distinct species.

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New Deep-Sea Fish Species Found in Antarctica

To catch Antarctic toothfish, you must bait your hook with Peruvian squid and cast it into the depths of the Ross Sea. This is what a team of Ukrainians did on a fishing trip near Antarctica. But sometimes, Mother Nature trips you up. Sometimes, you catch a hopbeard plunderfish. 

In 2009-2010, Ukrainian mariners happened to pull up three fish that looked unfamiliar. Further analysis found that they were a previously undiscovered species, dubbed the hopbeard plunderfish and described in a study published online April 29 in the journal ZooKeys. The fish bear the scientific name Pogonophryne neyelovi. 

The strange-looking denizens of the deep have brownish-splotched bodies and are shaped somewhat like tadpoles, especially when young, according to the study. They have sharp dorsal fins that extend along the top of their bodies and strange "barbels," which resemble dirty Q-tips, that extend from their chins. 

The longest of the three specimens measured 14 inches (35.5 centimeters). And they really like to live in the deep — they were pulled from depths of up to 4,560 feet (1,390 meters). 

This newfound species is the hopbeard plunderfish

 (Pogonophryne neyelovi). It can live nearly a mile 

under the surface of Antarctica's Ross Sea. 

CREDIT: Gennadiy Shandikov and Richard Eakin / ZooKeys 

The fish have large livers, which fill up to 35 percent of their abdomen. Whether or not that means these sea creatures could drink like, well, fish, is unknown. 

If you're fond of the hopbeard, just wait until you meet its cousins. The genusPogonophryne, also known as the short-barbeled plunderfish, has a total of 22 species. These fish also live in the frigid waters surrounding Antarctica. Some of them live in the Ross Sea, like the hopbeard, which is found offshore of Antarctica's Ross Ice Shelf. 

Currently, next to nothing is known about their behavior, diet or what they do down there in the depths. 

Continued: http://www.livescience.com/29456-strange-new-fish-antarctica.html

Evolution trumps ecological influence in deep-sea fish

AN INVESTIGATION by UWA scientists into factors which affect eye size in certain deep-sea fish has found that eye size varies based on the individual fish’s evolutionary status, rather than ecological pressures.

Researchers at the UWA Oceans Institute studied how types of Lanternfish (Myctophidae) have visually adapted to navigating the ocean’s mesopelagic zone (200m-1000m) where sunlight diminishes exponentially with depth.

The mesopelagic region or Twilight Zone has the greatest density of bioluminescent emissions, or light emitted by the animals themselves, which they use to interact with prey and predators.

They examined 237 members of the Lanternfish family spanning 61 different species, with eye and lens diameters ranging from 0.6mm to 11.1mm, and were collected from research cruises in different parts of the world including in the Coral Sea.

UWA PhD student Fanny de Busserolles says while in the field she had noticed significant differences in eye size compared to body size between different Lanternfish species and wanted to investigate the difference.

“Knowing that a larger eye will be more sensitive we thought there might be a connection between the amount of light present in the environment [sunlight or bioluminescence] and the relative eye size of a species,” she says.

“We hypothesised that species with a deeper distribution in the mesopelagic zone and/or a reduction of bioluminescent emissions will have smaller eyes, and that ecological factors rather than the evolutionary history of the family will drive the evolution of their visual system.”

The study found there was great diversity in eye size among Lanternfish at all taxonomic levels including the subfamily, tribes and genus.

But contrary to their expectations the team did not find a link between the eye size and the depth/luminous tissue patterns on the fish identified.

“A strong phylogenetic signal was observed for the eye size variable suggesting that this characteristic may be mainly influenced by the evolutionary history of the family instead of the ecological factors as we expected,” Ms Busserolles says.

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Ecologists Capture First Deep-Sea Fish Noises

ScienceDaily (Jan. 26, 2012) — University of Massachusetts Amherst fish biologists have published one of the first studies of deep-sea fish sounds in more than 50 years, collected from the sea floor about 2,237 feet (682 meters) below the North Atlantic. With recording technology now more affordable, Rodney Rountree, Francis Juanes and colleagues are exploring the idea that many fish make sounds to communicate with each other, especially those that live in the perpetual dark of the deep ocean.

Though little is known at present about the significance of sounds made by deep-sea fishes, Rountree and Juanes say that if, as their pilot study suggests, these tend to be low-amplitude, then man-made noise in the oceans may turn out to be a particular problem for some important species.

Their paper appears in the new book, "Effects of Noise on Aquatic Life," from Springer Science+Business Media in its "Advances in Experimental Medicine and Biology" series. It compiles papers from an international workshop in Ireland in 2010.

Using hydrophones deployed by fishermen during normal fishing operations, Rountree, Juanes and colleagues obtained a 24-hour recording in Welkers Canyon south of Georges Bank that yielded "a wealth of biological sounds" including sounds of fin, humpback and pilot whales, dolphins and examples of at least 12 other unique and unidentified sounds they attribute to other whales or fish.

Their new paper includes graphics showing the number of these grunts, drumming and duck-like calls recorded per minute by time of day, plus peak volume and frequencies of various noises. Some of the sounds exhibited strong temporal patterns, for example fin whale and dolphin sounds dominated the recording and peaked at night.

Continued:  http://www.sciencedaily.com/releases/2012/01/120126142908.htm