Questions tagged [marine-biology]

The study of organisms that dwell in the ocean or brackish waters.

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0answers
87 views

Why do most fish move fins orthogonally with their axis of symmetry?

So recently I read the question why are most fishes vertical (in the sense of distribution of their body mass) and it got me thinking what is the reason behind the direction they move their fins. My ...
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1answer
107 views

What forms the base of the coral reef ecosystem?

Corals are small animals that form a symbiotic relationship with algae. The algae produce sugars for the corals and are in turn provided with needed nutrients and protection from predators. That's ...
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Why are there relatively more predators on the land than in the oceans? [closed]

Our biology teacher told us that among worse conditions one of the reason that intelligent life had actually evolved on land is that there is a more important selective pressure due to the bigger ...
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1answer
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The colour of aquatic plants found deep under oceans

I have read that many aquatic plants found in deep oceans are red in colour, however, I do not understand why. As red is the color which gets the least scattered it should be the only light available ...
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1answer
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What strange jelly-like thing is shown in the photo?

What is shown in the pictures below? The photo was taken at the Australia's south coast (Queenscliff). The length of the thing is no longer than 50 cm... It doesn't move and has jelly-like consistency....
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Can jellyfish sting outside of water?

According to my understanding of the Wikipedia page on the stinging cells of the jellyfish, the mechanism of delivering the toxic missile is largely due to water pressure. Does that mean that a ...
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The effect of depth on net primary production in aquatic ecosystems

The figure shows the relationship between the water depth and net primary production (=P-R). I want to know why the production (P) initially increases with water depth near the surface? I have seen ...
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489 views

Can certain jellyfish photosynthesize in the medusa stage?

Can jellyfish (at least some of them) do photosynthesis in the symbiosis with zooxanthellae in their medusa form as well? I've heard that only Cassiopea andromeda can but I wasn't able to find a ...
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1answer
78 views

Was mammal body better suited for some type of the marine environment than the body of fish?

When some of the land mammals came back to the oceans, they seem to be successful in the competition with fish at least in some environment even though they seem to have a huge disadvantage in the ...
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Can the calcification response of a marine organisms, at different pH conditions, be assessed by the calcium magnesium ratio?

Can the calcification response of a marine organisms, at different pH conditions, be assessed by the calcium magnesium ratio? the calcium magnesium ratio is a proxy of calcification?
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1answer
108 views

Fish ID? Small, yellow-finned, tropical fish in Thailand

I have not had any luck finding the yellow fish shown in the photo in any of my fish books. I saw them in many places, so they are fairly common. This observation was at around 15 meter depth. I hope ...
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1answer
245 views

Identification of Bioluminescent Species in South Carolina Marshlands

I was in the brackish marshlands in South Carolina and the water was lit with short flashes of greenish bioluminescent light from a species that seemed to be floating in the current. The lights ...
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1answer
254 views

help identify this fish

I came across this washed up fish in Panama City, Florida in November 2015. I'm guessing it's a puffer fish but I can't find anything like it online. Thanks.
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1answer
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What are the migratory patterns of Orcas in the Pacific Northwest? Do they pass by Vancouver in the Fall?

What are the migratory patterns of Orcas in the Pacific Northwest? Do the pass by Vancouver in the Fall? I know you can never predict the sightings of a wild creature, but I was wondering what the ...
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132 views

Why are brightly coloured marine animals thought not to display aposematism?

There are many brightly coloured marine animals, such as fish, corals, sea stars, and octopodes. And yet Wikipaedia says it is thought that those colours don't serve to deter predators, while they do ...
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1answer
287 views

How do marine mammals and penguins maintain bone density?

After much searching on Google with no results, I decided to ask my question here. If I'm not mistaken, swimmers' bone density is less than normal; at least for lifetime swimmers. Astronauts also ...
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1answer
1k views

Is there evidence to suggest that sharks from prehistoric times live in the deep of the oceans?

I've had friends see the boat and giant teeth of a giant shark attack of a boat in Japan. (Teeth larger than a great white). [I can't find anything about this on the Internet]. In addition, this ...
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104 views

Is there more diversity in marine species?

I was reading about how life emerged from oceans, and the following question occured to me. Do land species suffer from the founder effect and is there more (genetic) diversity in marine species? A ...
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60 views

marine animal tracking databases

Which databases you know that store data on tracking of marine animals? I am interested particularly on mammals (for which I know meop storing data on sea lions) but also on fish schools (not sure ...
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303 views

Mangroves and desalination of sea water

I am not an expert but I guess that mangroves (or some other plants that thrive in sea water) perform some kind of desalination to extract fresh water from sea water. Is this true? If yes, What ...
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What do sharks not like the smell of?

I was reading about the sharks strong sense of smell ( Shark senses - @EnhancedLearning.com ) and wondered if any research has been done into what they don't like the smell of? Is there any material ...
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1answer
255 views

Species identification - greenish blue ocean worm (nudibranch?) in Perhentian Islands, Malaysia

We found this on a beach at the Perhentian Islands, Malaysia in March, 2016 and cannot identify it. It's some sort of worm-type creature with many legs and bluish back about 15cm long. The legs ...
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How long can an octopus survive out of the water?

I saw videos of octopuses crawling on the ground and I was wondering how long an octopus can survive when out of the water? Does it depend on either its size (i.e., does a big octopus from deep sea ...
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1answer
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Is this a saltwater millipede?

I spotted this millipede-like creature in Hervey Bay, Australia at low tide, just kind of hanging out at the bottom of a small saltwater tidepool. It's several inches long, composed of a large ...
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Why are oceans said to have “low productivity” in terms of photosynthesis?

80% of the world's photosynthesis takes place in the ocean. Despite this, oceans are also said to have low productivity - they cover 75% of the earth's surface, but out of the annual 170 billion ...
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Can immortality of the Turritopsis dohrnii be learned or adapted by other species?

I have heard that Turritopsis dohrnii is a species of jelly fish which is immortal, as it can grow old and then back to growing young. So, how is it possible? Can other species (marine and/or land) ...
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Where should one start if they want to go about identifying phytoplankton and dinoflagellates?

I'm a first year university student and I really need help on how to identify and recognize the different organisms observed in my water samples. Are there any good references/tips on how to?
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218 views

What happened to this seashell?

We found this seashell on a Mediterranean beach in the south of France. While most of the shells we found were quite intact, this one caught our attention. It is light and littered with tiny holes, ...
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2answers
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Colourful aquatic animal identification

Of what species is the following creature? I expect it would be a Cephalopod living in not too deep water with a tropical climate (Brazil?). However, I can not find any information about what species ...
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1answer
292 views

What would be the impact of depositing limestone in the oceans (to reverse acidification) on ocean life forms and biodiversity?

This question asked: What is the evidence it is feasible to reverse ocean acidification by adding large quantities of a base (bicarb soda)? The result was: Danny Harvey of the University of ...
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1answer
167 views

Best tail for swimming?

I understand that the vertical tails of fish and the horizontal flukes of cetaceans evolved due to the spinal movements of their ancestors but I was just wondering if there has been any investigation ...
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423 views

Why are oceans carbon sinks?

Building on this question, I understand pretty clearly why forests are carbon sinks (trees grow, and there is carbon stored in soil and biomass). What about the oceans, though? Are underwater ...
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1answer
2k views

Do rare earth metals actually repel sharks? [closed]

Stroud claims that sharks are effectively repelled by the use of rare earth metals in the water. There has even been a patent issued by the same author for rare earth-wrapped fish hooks to reduce the ...
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Neuston vs pleuston

I was recently reading about the wonderful chondrophores, and came across the terms "neuston" and "pleuston". According to Wikipedia, "neuston" are "the organisms that float on the top of water ... ...
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1answer
722 views

What is the convention for log notation in biology?

I'm reading through some oldish (1980s) papers on length-weight relationships in fish and crustaceans. Many report log-log relationships without specifying whether this is natural log, base 10, etc. ...
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1answer
646 views

Selection Pressure on Orca Whale Coloration

What is the proposed selection pressure that leads to the distinctive coloration of Orca whales? I can find nothing in the literature.
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670 views

What fish (and/or shellfish) species with a multi-year life-cycle, besides salmon, die after spawning?

Most species of salmon die after spawning. Are there any other types of fish that spawn once and then die after a multi-year life-cylce? Is this a rare life history strategy among our human exploited ...
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1answer
2k views

How can a brainless Cnidarian hunt and defend itself?

Cnidaria, such as jelly fish and sea anemones are radial symmetric en feature a simple body plan. One notable aspect is the lack of a brain. Hence, there is no central guiding structure, no mind or ...
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758 views

How do diving marine mammals avoid decompression sickness?

How do marine mammals, whose very survival depends on regular diving, manage to avoid decompression sickness or "the bends?" Do they, indeed, avoid it?
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How do marine mammals control buoyancy?

Presumably, as a whale or seal dives, its lungs get compressed by the increasing water pressure, and it gets less buoyant. Under this model, for a given amount of air taken in at the surface, the ...
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2answers
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How and why did mammals go back to the oceans?

If I understand evolutionary biology correctly, mammals first evolved on land as small, rodent-like creatures, in a time when reptiles were dominant on land. Eventually, they diversified into the ...
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2answers
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Effect of extremely hard water on marine life?

When researching water quality standards, I found that a minimum and maximum was set for water hardness. Several sources also state that water can in fact be too hard. The question is how does hard ...
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1answer
540 views

How long does it take for a hard clam (Mercenaria mercenaria) to reach sexual maturity?

How long does it take for a wild hard clam (Mercenaria mercenaria) to reach an age where they are reproductive? How does fecundity depend on age and size? I've looked at several hard clam life cycles ...
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What are the buoyancy control mechanisms of Chambered nautilus?

I'm currently working on an underwater robot and was hoping to use the principle used by the nautilus for buoyancy control. So how do the Chambered nautilus control its buoyancy?
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Age of shells on beach

As a child I watched tiny fiddler crabs living in conical shells, and many years later I find that people study fossil turritellids. So now I wonder: how old are shells, typically, that you see on ...
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1answer
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How does the Cuttlefish camouflage itself accurately despite being color-blind?

I have seen/read that the Cuttlefish is able to camouflage itself extremely accurately. I have also seen/read that they are completely color-blind, though see with very high contrast. How does the ...
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2answers
474 views

Why is oxygen used up in eutrophication?

This probably sounds pretty dumb, but wouldn't algae blooms produce a lot of oxygen? Although they would die out and decomposers would use up oxygen, is that more than what the algae produced?
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130 views

Is there any documented case in which floating substances led to the introduction of a new species?

Floating substances in the marine or freshwater environment often carry hitch hiking organisms. It is argued that many species may use this dispersal vector to reach new habitats, however to my ...
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What is the fastest marine mammal?

When I did a research, most of the sources say that orca is one of the fastest. But I could not find a source that says it is actually the fastest. Some sources say that Dall's porpoises rival orcas ...
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118 views

Can viruses be used to extract oil from algae?

I read that one hard step in algae oil extraction is to rupture (or fracture) the cell walls to get the contents inside. Some people use chemical methods; some use sonication or mechanical forces. I ...