Navigation Links
Ocean seep mollusks may share evolutionary history with other deep-sea creatures

The unusual mollusks of oceanic cold seeps--strange clams, mussels and sea snails that thrive in the sulfur and methane-rich environments--are on average older than the marine mollusk community as a whole, according to a new report in the 8 September issue of the journal Science, published by AAAS, the nonprofit science society.

On average, the first appearance of cold seep mollusk genera in the geological record is a full epoch earlier than that of marine mollusks in general, according to Steffen Kiel and Crispin Little of the University of Leeds.

These findings indicate that the long evolutionary history of the seep mollusks is more similar to that of other deep-sea animals than to some of their mollusk contemporaries from other parts of the oceans.

Cold seeps may have been--and continue to be--safe harbors for the mollusks, protecting them from mass extinctions and possible abrupt oxygen changes in the seas, the researchers found. However, many deep-sea species outside of the cold seeps have also managed to ride out these changes.

"The shallow water environment is much more challenging, subject to changes in sea levels, extinction events, pollution, sediment runoff--all sorts of factors which don't affect animals in the deep sea," Little explained.

This makes it difficult to tell whether seep mollusks owe their long evolutionary history to their unique home environment or to their status as deep-sea creatures, he noted.

Cold seeps are places where fluids rich in hydrogen sulfide and methane leak up through the ocean floor, creating a unique chemical environment where hardy bacteria process the sulfide and methane. Seep fluids are about the same temperature as surrounding waters, but similar chemically challenging environments exist at hydrothermal vents, fissures in the ocean floor where water is superheated by magma lurking just below the crust.

Although seep and vent fluids are a poisonous brew for most sp ecies, animals such as giant tube worms and the mollusks studied by Kiel and Little thrive with the help of the symbiotic bacteria. "If you can become adapted to living at these sites, you can make a very good living indeed," Little said.

The origins and age of seep citizens such as the mollusks has been debated for some time by scientists using both fossil and genetic evidence. Kiel and Little decided to examine the fossil record for modern seep mollusks to see how their history compared to that of the overall marine mollusk population.

By sorting 29 mollusk genera into the geological time periods when they first appeared, the researchers found that seep mollusk genera, on average, appeared during the Eocene epoch about 55 to 34 million years ago. By contrast, the average age of first appearances for all marine mollusks occurred in the Oligocene epoch, about 34 to 24 million years ago.

Following the fortunes of seep mollusks through time, Kiel and Little also found little evidence that mass extinction events or periods of low oxygen dealt significant blows to the seep communities. Seeps may have been good shelters during these events because "they were driven by a constant source of geothermal energy," Little said.

The Eocene age calculated by the Science researchers casts some doubt on another mystery involving seep animals: what is their relationship to whale falls? Whale falls, the slowly decaying remains of large whales sunk to the ocean's depths, harbor yet another unique chemical community similar to that in vents and seeps.

Some researchers suggest that whale falls were evolutionary "stepping stones," creating new environments for seep animals to evolve into a plethora of new species. But Kiel and Little's work shows that more than three-quarters of seep mollusk genera had already appeared by the time oceangoing whales would have filled the seas.

Whale falls "are not instrumental in the evolution" of seep mol lusks, but the falls "may have allowed them to expand into new sites," Little explained.

"Cold seep mollusks are older than the general marine mollusk fauna" by Steffen Kiel and Crispin T.S. Littleat the University of Leeds.


Source:American Association for the Advancement of Science

Related biology news :

1. Oceans more vulnerable to agricultural runoff than previously thought, study finds
2. Breakthrough System for Understanding Ocean Plant Life Announced
3. Ocean climate predicts elk population in Canadian Rockies
4. New Scripps Oceanography project to study sediments and ecosystem restoration in Venice lagoon
5. Oceans turning to acid from rise in CO2
6. The Antarctic Ocean floor
7. Ocean dead zones trigger sex changes in fish, posing extinction threat
8. Oceans are 70 percent shark free
9. Ocean virus identified in human blood samples
10. MIT: Oceans are a major gene swap-meet for plankton
11. Ocean acidification threatens cold-water coral ecosystems
Post Your Comments:

(Date:11/19/2015)... , Nov. 19, 2015  Based on its ... & Sullivan recognizes BIO-key with the 2015 Global Frost ... year, Frost & Sullivan presents this award to the ... catering to the needs of the market it serves. ... line meets and expands on customer base demands, the ...
(Date:11/17/2015)... 2015 Paris from 17 ... Paris from 17 th until 19 ... innovation leader, has invented the first combined scanner in the ... same scanning surface. Until now two different scanners were required: one ... capture both on the same surface. This innovation is ...
(Date:11/16/2015)... Nov 16, 2015  Synaptics Inc. (NASDAQ: ... solutions, today announced expansion of its TDDI product ... touch controller and display driver integration (TDDI) solutions ... These new TDDI products add to the previously-announced ... TD4302 (WQHD resolution), and TD4322 (FHD resolution) solutions. ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... ... November 24, 2015 , ... In harsh industrial processes, ... for in-line sensors can represent a weak spot where leaking process media is ... retractable sensor housings , which are designed to tolerate extreme process conditions. They ...
(Date:11/24/2015)... Nov. 24, 2015 HemoShear Therapeutics, LLC, ... drugs for metabolic disorders, announced today the appointment ... Board of Directors (BOD). Mr. Watkins is the ... Genome Sciences (HGS), and also served as the ... Jim Powers , Chairman and CEO of HemoShear ...
(Date:11/23/2015)... -- Women with a certain type of lung nodule visible ... of lung cancer than men with similar nodules, according to ... meeting of the Radiological Society of North America ... --> Lung nodules are small masses of tissue in ... on their appearance on CT. Solid nodules are dense, and ...
(Date:11/23/2015)... November 23, 2015 The royalty-free ... to develop daclatasvir for 112 low- ... --> --> The Medicines ... hepatitis C medicine, signing an agreement with Bristol-Myers Squibb for ... cure multiple genotypes of the HCV virus.  The royalty-free licence ...
Breaking Biology Technology: