49
votes
Accepted
How long can an octopus survive out of the water?
Short answer
Under ideal conditions, an octopus may survive several minutes on land.
Background
Octopuses have gills and hence are dependent on water for the exchange of oxygen and carbon dioxide. ...
- 52.3k
45
votes
I am trying to identify this bone I found on the beach at the Delaware Bay in Delaware. It is 2 1/2 inches wide and 1 1/2 tall
It's a pharyngeal tooth from a large fish like a drum or a parrot fish.
The pharyngeal jaws are for grinding and also contain a pharyngeal mill, where larger and smaller teeth grind coarser and finer ...
- 10.3k
37
votes
Accepted
What is this strange sea creature we found on the beach?
You have a Dosima: Also known as a Buoy Barnacle. A gallery of observations of these can be found here:
https://inaturalist.ca/taxa/462188-Dosima/browse_photos
They are found in the coastal UK and ...
- 1,856
28
votes
A weird-looking fish with a shield
This is a species in the Peristediidae family, commonly called armored searobins or armored gurnards.
found in deep waters around the world, with most species in tropical regions. They are related to ...
- 29.7k
26
votes
Accepted
Identify blue/translucent jelly-like animal on beach
By-the-wind sailors
This appears to be Velella (a monospecific genus), commonly referred to as by-the-wind sailor.
More specifically, this is Velella velella, and is also less commonly referred to ...
- 29.7k
22
votes
What exactly is this small puffer fish doing and how did it manage to accomplish such a feat?
A tiny Japanese puffer fish creates a grand sand sculpture on the featureless seabed by using his fins to dig furrows. He uses this to attract the attention of passing females.
Why do puffer ...
- 1,562
21
votes
Accepted
What strange jelly-like thing is shown in the photo?
I agree with @Gerardo-Furtado's comment that what you most likely have here is a colonial tunicate (or sea squirt) from the genus Botrylloides.
According to images and information available via the ...
- 29.7k
20
votes
Accepted
Identification of colorful jelly-like marine creature
You've found a sea anemone, a cnidarian of the Order Actiniaria. In this case, the anemone is closed and thus hiding its characteristic tentacles (likely as a form of protection while "out to dry").
...
- 29.7k
20
votes
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Inexperienced divers damage coral, but parrot fish eating coral doesn't do damage?
You are absolutely correct in regards that marine life does cause damage to corals. In particular, parrotfish have been found to play an important role in regulating the biodiversity of coral reefs ...
- 1,007
18
votes
Accepted
What's this stuff that looks like white chainmail armor growing on giant kelp?
That looks like it could be the lacy crust bryozoan (Membranipora membranacea). That bryozoan is an epiphytic animal whose native range includes the Pacific coast; it does not feed on the kelp, but ...
- 5,577
16
votes
What exactly is this small puffer fish doing and how did it manage to accomplish such a feat?
This "nest" is created by a male pufferfish for both courtship and for rearing young.
The male puffer fish uses its body and fins (a combination of pectoral, anal, and caudal -- see here) to ...
- 29.7k
16
votes
Accepted
Why does biomagnification of mercury occur more in large fish?
Bioaccumulation occurs when organisms aren't able to excrete/eliminate/metabolize something as fast as they take it in. The specific circumstance of predators higher on the food chain accumulating ...
- 44k
12
votes
Why are the bodies of the Risso's dolphin covered in scratches?
[ From Jefferson et al. 2015, Marine Mammals of the World, 2nd edition, p 212: "At sea, the best identification characteristic is the coloration and scarring. Adult Risso's dolphins range from dark ...
11
votes
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Help identify these (two) fishes - Netherlands
The second fish looks like a rock gunnel (or Butterfish; Pholis gunnellus).
This is an eel-like fish found in the intertidal and subtidal zones of the North Atlantic.
Interestingly, the rock gunnel ...
- 29.7k
11
votes
What sea animal is this?
It's probably a dugong, based on the location, lack of a dorsal fin, split tail, lack of a blowhole, and narrowing of the snout.
The prominent vertebral column looks unusual, but that might come from ...
- 44k
11
votes
Found this under a rock at the beach, removed it carefully and couldn't find any other bones, must be a marine mammal of some sort
A reasonable match for many features, bearing in mind the incompleteness of the skull is that of the South African Fur Seal (AKA. brown fur seal, Australian fur seal).:
Carolyn Stewardson, Tania ...
- 1,485
10
votes
How long can an octopus survive out of the water?
Found an octopus today which had attached itself to a rock covered in algae during high tide and had failed to swim back out with the receding tide. We found it at low tide, this means it must have ...
- 101
10
votes
Accepted
Deflated bag-like species on beach: Identification
Sea cucumber.
There are over 1700 known species, all inhabiting the sea-bed, mostly in deep waters, but can be found on the continental shelf in many areas.
An echinoderm (alongside sea-urchins and ...
- 1,485
10
votes
Accepted
Identification of a strange skull
Looks like this is a neurocranium of a tuna or a similar species (dorsal view on this site).
I've also found a very similar picture of Atlantic blue tuna from USA, which seems to support that this is ...
- 431
9
votes
Accepted
Can jellyfish sting outside of water?
Short answer
Jelly fish can sting out of the water and even when they are considered to be dead.
Background
I do not have detailed scientific literature available. However, popular sources generally ...
- 52.3k
9
votes
Accepted
The colour of aquatic plants found deep under oceans
You're right that certain wavelengths of light are more capable of penetrating deeper depths of water. However, it turns out, blue light typically travels to deeper depths than all other visible ...
- 29.7k
9
votes
Accepted
What happened to this seashell?
The holes are probably caused by one of a family of parasitic sponges. The holes, as you'd expect, kill the oyster, and the sponge then takes up residence in the shell. A number of species of this ...
- 14.2k
9
votes
ID a shell from Puerto Rico
This is the shell of a marine mollusk called a chiton.
They are also sometimes known as sea cradles or "coat-of-mail shells", or more formally as loricates, polyplacophorans, and ...
- 29.7k
8
votes
Do fish depend on plants for survival?
Yes, photosynthesis provides nearly all of the ocean's biomass and energy. The best is to study oceanic food chains and webs.
It looks like there aren't enough plants in the ocean because they don't ...
- 10.3k
8
votes
Accepted
Why do blobfish become bloated when they are brought to the surface?
Blobfish don't have swim bladders, they also don't have a lot of other things we associate with surface animals, like much of a skeleton or many muscles. This is fine under the extreme pressure they ...
- 14.3k
8
votes
What are these semi transparent pill-shaped things in the Mediterranean Sea?
Quick guess based on your low-quality photo:
Reminds me of a pyrosome, a tube/rod-shaped, free floating colonial tunicate.
According to here, Pyrosoma atlanticum is the only species found in the ...
- 29.7k
7
votes
Accepted
Age of shells on beach
Mollusk shells found on typical east coast (US) beaches can range from days old (the animal that made the shell died recently) to thousands of years old. Some shells in our state, North Carolina, ...
- 86
7
votes
Why is oxygen used up in eutrophication?
Algae produce $O_2$ in the upper layer of water but when they die they stop producing $O_2$. They sink to the seafloor and most get decomposed by bacteria on the seafloor. In this process, bacteria ...
- 867
7
votes
Accepted
Organic battery?
I don't have the math at hand for the actually energy efficiency, but let's just start from the storage capacity.
Basically, an electric eel wouldn't make a very good battery. They could be a decent, ...
- 44k
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