Sea Slug Adaptations Offer Insights for Medicine and Technology

Key Quotes

"First of all their diversity is vast with an estimated 10,000 different species some are smaller than a quarter and one species can weigh more than your terrier i'm talking 30 pounds and as i say they come in vivid neon colors with patterns that rival the most beautiful butterflies come complete with feather like external gills and tentacles not to mention their usefulness in brain research understanding their neural networks was the basis for a nobel prize."

Ira Flatow highlights the impressive diversity and striking appearance of sea slugs, contrasting them with the common perception of garden slugs. He notes their significant size range and their unexpected utility in scientific research, specifically mentioning their neural networks as a foundation for a Nobel Prize.

"Yeah this was a rough one for me i got to read that paper and um i had collected many crawling severed heads of slugs over the years and i always thought i had done it like i had damaged the slug in collecting and as soon as i read this work it was like oh i was meant to discover this damn this has now been shown in many different species that in the group that i work on embarrassingly enough when their bodies become sufficiently old and riddled with parasites they can pop off their head ditch their old decrepit body and regenerate an entire new body full new clean set of organs and reboot themselves in a matter of a week or two and get a whole new start on life with their same brain but everything else is new and they're the most advanced organisms that we know of that are capable of that level of regeneration."

Dr. Patrick Krug describes the remarkable ability of certain sea slugs to detach their heads and regenerate an entirely new body. He expresses personal surprise at this discovery, noting that this advanced form of regeneration, where the brain is preserved while the rest of the body is replaced, makes them unique among known organisms.

"The difference really is that the sea slugs have to contend with an ocean full of hungry fish that are trying to eat them all the time and the solution that they have evolved to life without a shell is that almost every species lives in a strict partnership with their food so there are sea slugs that feed on fish and they have to grab a hold of a little goby fish to suck the fluids out of it and they ride around on the back of a fish there are sea slugs that are free swimming and live their life in the open water in the middle of the ocean that are called sea butterflies there are sea slugs that can suck up the chloroplasts from seaweed that they feed on and keep them alive in their own bodies and become photosynthetic and can go months without eating and just live off of sunlight."

Dr. Patrick Krug explains that the vibrant colors of sea slugs are a defense mechanism against predators in the ocean. He details how many species have evolved to survive without shells by forming specific partnerships with their food sources, some even incorporating chloroplasts from seaweed to become photosynthetic and sustain themselves on sunlight.

"We do and we have there are fda approved cancer drugs now that were originally isolated from sea slugs from their defensive chemistry and from the food that they eat and i think in the future there will be even more there is a lot of research that's been done on these compounds and one of the kind of interesting quirks of this area of study is the slugs will often find a thing that we can't necessarily find easily like a very tiny seaweed that's very hard for humans to collect but the slugs will find it and store its chemistry and we can find the slug so they are very good collectors of obscure things and they store the chemistry in a way that makes it easier for humans to find it and then to study its potential medicinal properties."

Ira Flatow discusses the medicinal value derived from sea slugs and their diets. He points out that FDA-approved cancer drugs have originated from the defensive chemicals found in sea slugs and their food sources, and that these slugs act as efficient collectors of obscure, hard-to-find natural compounds beneficial for medical research.

"All sea slugs are hermaphrodites so they are all simultaneously male and female and that leads to some sort of interesting complications any two slugs or more that encounter each other can always reproduce together but it's also complicated right because you have the option to be the male or the female or both and so how they resolve that is different in different groups sometimes they they trade sperm and fertilize each other's eggs sometimes they get into these sort of violent tussles in some groups slugs will inject manipulative chemicals into their partner to try to um basically make them relax and adopt one sex role it's a little astonishing how how often some of these things evolved too some slug groups have evolved hypodermic insemination where they can inject sperm anywhere on the body of another slug in what's called hit and run mating wow yeah like pardon me do you have the time doink now you're pregnant and i'm crawling on my way and this has evolved in a lot of different groups."

Dr. Patrick Krug explains that all sea slugs are hermaphrodites, possessing both male and female reproductive organs. He describes the complex reproductive behaviors that result, including sperm trading and fertilization, as well as more aggressive tactics like the injection of chemicals or sperm into a partner, a phenomenon known as traumatic mating.

"They are kind of fascinating they're outliers in their size so they can grow to be the size of footballs or even basketballs in the case of the really big sea hares like the black sea hare aplysia vaccaria that we have here in california where i am they are vegetarians they eat seaweeds so one of their very unusual characteristics is they can exude ink that can be like a bright purple in some species it can be really beautiful actually and they exude other substances that can do things like they can blind the antennae of lobsters as a defense no kidding and they have these extraordinarily large their called neuromuscular junction it's where the nerves touch the muscles and they're large enough you can actually see them they can be like two millimeters in size yeah eric kandel won the nobel prize for that yeah about 25 years ago that work was recognized how big they were because it makes them so easy to study you know if you think about the size of a human nerve those fibers are so tiny it's difficult to manipulate them to like stick a needle or a probe into a nerve cell is very hard but if that nerve cell is huge it's just a much more tractable system to study."

Ira Flatow introduces sea hares as exceptionally large sea slugs, some reaching the size of basketballs. He highlights their unique defense mechanisms, such as exuding purple ink and substances that can blind predators, and notes the extraordinary size of their neuromuscular junctions, which made them ideal subjects for Nobel Prize-winning research on nerve cell function.