Could a mature (and giant) lobster remain in sea water indefinitely without decaying?

Question

My pantheon of storyline gods includes a "titan" of sorts, in the form of a giant lobster. At one point in time, she returns to the coastal ocean and exists in a meditative state on the seafloor for several centuries, possibly even a millennia.

Would her exoskeleton be capable of enduring the saltwater for that long? What would she look like after a few hundred years of submersion? As is typical with living organisms, decay is inevitable. I don't want to have to incorporate too much "god-like" magic into her character aside from what I already have.

Answer 1

What would she look like after a few hundred years of submersion?

Like a really big lobster. Regular lobsters live in the sea, and can live to over 100 years old and still look just like lobsters. They just get slightly bigger and slightly heavier after each moult. Normal crustaceans stop moulting eventually (perhaps due to sensescence, or perhaps due to the sheer effort of getting bigger each time... what does your titan eat?) and so will reach a maximum age, but that restriction need not apply to your special case of a godlike titan. Note that moulting means the old exoskeleton is lost and a new one is exposed instead; the outside of your lobster won't be centuries or millenia old unless the moults are that infrequent.

As is typical with living organisms, decay is inevitable

Well, ultimately you'll reach the issue of the sun expanding and swallowing the earth so practically living forever is awkward, but given that the most ancient living organism on earth is over 5000 years old there's plenty of scope for long life in things that can grow, fight off disease and repair themselves.

Answer 2

You should read the wiki for biological immortality:

Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, including some vertebrates, achieve this state either throughout their existence or after living long enough. A biologically immortal living being can still die from means other than senescence, such as through injury, disease, or lack of available resources.

Interestingly, the article cites lobsters:

Research suggests that lobsters may not slow down, weaken, or lose fertility with age, and that older lobsters may be more fertile than younger lobsters. This does not however make them immortal in the traditional sense, as they are significantly more likely to die at a shell moult the older they get (as detailed below).

Their longevity may be due to telomerase, an enzyme that repairs long repetitive sections of DNA sequences at the ends of chromosomes, referred to as telomeres. Telomerase is expressed by most vertebrates during embryonic stages but is generally absent from adult stages of life. However, unlike vertebrates, lobsters express telomerase as adults through most tissue, which has been suggested to be related to their longevity. Contrary to popular belief, lobsters are not immortal. Lobsters grow by moulting which requires a lot of energy, and the larger the shell the more energy is required. Eventually, the lobster will die from exhaustion during a moult. Older lobsters are also known to stop moulting, which means that the shell will eventually become damaged, infected, or fall apart and they die. The European lobster has an average life span of 31 years for males and 54 years for females.

So all you need to do is find a way for your titanic lobster to either repair its shell or survive its moulting as it grows bigger - neither is too large a stretch. It could happen realistically. In our own world lobsters evolving to be gigantic might be improbable, but not impossible.

I just remembered that the ancerstors of crustaceans could grow up to 2m long. That they never grew bigger is a matter of evolutionary pressure, which could have happened differently in your world.

Answer 3

It could be that if she lives on the ocean floor and doesn't move, that the oceanic sediment that collected on her shell became home to many organisms, like choral, mollusks, etc, that have built up the protective barrier on her shell. Just think what a shipwreck looks like after only a couple hundred years.

That would also make her that much more imposing when she surfaces. "It was as if the ocean floor itself rose to the surface and sought revenge for humanity's transgressions" -- Old Sailor

Answer 4

The bigger an arthropod gets, the more trying the molting process is. A really big animal wouldn't have many places to hide, so perhaps the lobster could evolve a foul tasting and toxic skin underneath the exoskeleton. If you want it to be edible, it can go through hormonal changes before molting that makes it toxic, instead of all the time. A 200 year old lobster would be 29-89 lb and 22-31 in, a 300 year old lobster would be 43-151 lb and 25-36 in, a 1000 year old lobster would be 143-718 lb and 36-59 in. Real lobsters are not known to surpass 25 in and 44 lb and have a maximum recorded age of 140. No magic is needed, living animals don't normally decay and since crustaceans molt, nothing will really happen to the exoskeleton, although as the lobster gets older, it will molt less often, so the lobster will probably be covered in barnacles and similar animals.