University of Miami researcher Lynne Fieber holds a hatchery-reared California sea hare, Aplysia californica. (Michael Schmale)

Just in case sea snails aren't slow enough, new research has found that they get more sluggish when they grow old — and the discovery is helping us to understand how memory loss happens in humans.

It turns out that the sea snail, which has a one-year lifespan, is actually a good model to study nerve cells and how the nervous system works in people. How neurons work is fundamentally identical in almost all animals, and the simplicity of the snail's body gives researchers the chance to view how different the system works more directly.

"You can count the number of nerve cells that are relevant to a reflex," said Lynne Fieber, a professor at the University of Miami who leads research with the snails at the school.

[This invasive giant snail is spreading in Florida – and bringing nasty parasites with it]

She and a team of researchers have been using the slimy little critters to learn how nerve cells respond to electric shock. They "taught" the snails to quickly contract their muscle tails by administering electric shocks and then poking the tails, a process called "sensitization." They then studied the responses at various ages.

The scientists, whose work was published this week in the journal PlOS One, found that as the senior citizen specimens do not learn to contract from the shock very well. As the snails grow older, their tail startle reflex lessened, and then disappeared.

So I guess you could say the frail snails' tails fail to avail (okay, I'll stop).

By studying the reflexes of the older snails, scientists were able to zero-in on the exact cells in the nervous system that stop working, highlighting where we need to look to understand the mechanics of age-related memory loss in humans.

"It's a thrilling discovery," Fieber said. "It's like pinpointing the source of the problem."

[Uh-oh: One of the world’s worst invasive species just showed up in the United States]

The plan is to continue the research, possibly to collaborate with other facilities to test human neurons, such as with stem cells.

But for now, it's worth taking a bit more time to look at the amazing creatures featured in the experiment. The researchers specifically looked at a species known as the California brown sea hare, named after two bunny-ear-like tentacles poking out the top of its head. They're usually a reddish-brown color and they can grow up to around five inches long.

Sure, that's pretty big for a snail, but it's nothing compared to it's cousin, the California black sea hare, which can grow up to 29 inches and 30 pounds.


Behold: the California black sea hare. (iStock)

But the little guys have an extra feature to one-up their gigantic relatives: their defense systems. Whenever the brown sea hare is in a bind, it ejects a cloud of purplish-pink ink to confuse its predators, like the spiny lobster. Scientists have found that there are amino acids in the ink, which trick lobsters into thinking they can ingest it. That could give the snail just enough of a diversion to scrunch away.

The University of Miami farms the magnificent creatures with the help of the National Institutes of Health, and it has around 20,000 of the specimens in its lab. The researchers periodically ship the snails off to scientists across the country, partially frozen and wrapped up in newspapers.

"It's like Christmas!" Fieber said.

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