Fresh Water Squid??

[chrisfagan16]

Hi, i was just wondering can you get fresh water squid. Thanks.

 

[Danno]

I dont know where you would get them but I would be afraid when the sqirt ink at you and poof your tank looks like dyarea

 

[cation]

There are no cephalopods in freshwater or estuaries, so you won't be finding one.

 

[Danno]

I guess youdont have to worry bout dyarea water then

 

[SirMinion]

dyarea

Is that supposed to be 'diarrhoea'?
Ewwwwww!

No, no squid or octopus for freshwater, which is a shame.

I wonder why they haven't managed to move inland, after all, they've been around for at least four hundred million years.

 

[cation]

I wonder why they haven't managed to move inland, after all, they've been around for at least four hundred million years.

You aren't the only one to wonder this....

"Hmm, yes, that is a weird question. I must confess that I had never really thought about why the cephalopods had never colonized estuaries and freshwater habitats, while other molluscan taxa (gastropods and bivalves) have become very successful there. While thinking about your question I reviewed my invertebrate zoology texts and came to the conclusion that the answer lies in some fundamental biological differences between the squids and the molluscs that have moved into and beyond estuarine habitats. I'll discuss three such biological constraints: mode of feeding, life history traits, and lifestyle.

Mode of feeding: Squids, as you noted, are fantastic raptorial predators. They pursue and capture individual prey items in the water column. Snails and bivalves, on the other hand, are much less specific in their feeding. Some snails are predators, but most are either grazers or suspension feeders. Bivalves are almost all suspension feeders. These generalist modes of feeding provide a dietary flexibility that may have allowed some gastropods and bivalves to invade estuaries and freshwater habitats.

Life history traits: Squids (and all cephalopods) are gonochoric, meaning that the sexes are separate. Many of the animal taxa that have successfully moved from marine into freshwater and terrestrial habitats are hermaphroditic. Hermaphroditism increases the likelihood of reproductive success because every conspecific encountered is a potential mate; whereas for gonochoric animals, only 50% (on average) of conspecifics encountered is of the opposite sex. This reproductive advantage is unavailable to squids.

Another aspect of reproduction that may have prevented squids from invading estuaries and freshwater systems is the fact that they are obligate copulators and lay egg capsules. The necessity of finding a mate, rather than just broadcasting gametes into the water column, in addition to having separate sexes, makes successful reproduction even more difficult. Komiushin and Glaubrecht (2003) cite other authors and suggest that, in molluscs, the transition from marine to brackish or freshwater habitats involves a concomitant transition from a long- lived planktonic larval stage to some form of incubation or parental care. Although squids undergo direct development and hatch as juveniles, they do have a lengthy planktonic phase during which they would be vulnerable to predators as would a planktonic larval stage.

Lifestyle: Squids are pelagic animals, spending their entire lives up in the water column. Freshwater gastropods and bivalves are all benthic, living on or (in the case of clams) in the bottom. Squids must forage in the water column, where they must compete with fishes for limited food resources. It may be that estuaries and freshwater habitats do not support enough plankton to feed two guilds of pelagic predators.

As is the case with many "Why?" questions, yours was fun to think about but difficult to answer. I hope I've given you something to think about, even if I was unable to give you a direct answer to your question.

Allison J. Gong
MAD Scientist"

This was taken from a google search - I could only get to the page through Google's cache, so I don't have the link, but the main site it's from is madsci.org

 

[SirMinion]

All interesting points, but all equally apply to thousands of species of fish, and they succesfully moved inland thousands of millions of years ago, so again, why not cephalopods?

 

[Dwarfs]

dyarea

Is that supposed to be 'diarrhoea'?
Ewwwwww!

Do you mean diarrhea?

 

[Michael Roth]

both are accepted. I would not wonder too hard, there are a gazillion other species that never made the transition.