Wentu / Wang Hao
Charles Darwin University, Australia
This article is from the May issue of Knowledge is Power magazine
As you may have heard before, scientists inspired by slugs have developed a heart "Band-Aid", a new material that can quickly adhere to stop bleeding while maintaining extremely high tissue and organ strength. So do you know what a slug is?
Banana slugs
What is a slug?
Slugs ( scientific name slugs [ kuò yú ] ) are mollusks of the mollusks Phylum gastropods , and are relatives of snails and conchs. Usually speaking of slugs refers to land-based life, and the "cousins" in the sea are called sea slugs. At first glance, the slug, sticky and soft beach, is really apt to be called "snot"!
The "cousin" of the sea - sea slugs
However, if you take a closer look at its body, from head to toe, there are many magical things. Let's explore it together.
antenna
Slugs, like snails, have two pairs of freely retractable antennae on their heads. In addition to being responsible for probing the things around the body, the top pair of long antennae has an eye point at the end, that is, a very simple structure of the photosensitive system; the bottom pair of short antennae have an olfactory function, mainly collecting sex hormones in the mucus trajectory left by slugs and the chemical odor emitted by the things around them.
Tongue (mouth)
The slug has a unique tongue in its mouth, the tooth tongue, which, as the name suggests, is densely covered with small barbs. The different kinds of slugs are arranged differently, which is probably related to their more complicated diets, after all, some eat vegetarian, some eat meat (eat other slugs, snails and earthworms). When eating, the slug sticks out its tongue and uses a fine barb to cut and transport the food into the mouth.
Shield plate (coat film)
The shield on the back of the slug is a remnant of the incomplete degradation of the shell (qiào) shell (ké), some protruding, others not very obvious. The more abrupt one is the breathing hole, which is so large that it opens on the side of the body (usually on the right). In fact, snails also exist, but people carry a shell, which is not easy to see.
Abdominal cavity (outer cavity)
Under the shield shield covers the nasolabial visceral and reproductive systems. An interesting phenomenon is that the slug's defecation and reproductive foramen are not in the lower part of the tail of the body, but are open on the top of the head forward or on the side of the body. Why?
The term Torsion in the medical and biological fields refers to the torsion of organs, such as the ovaries and testicles, which can occur with torsional symptoms. A common feature of gastropods is the 180-degree twisting of celiac tissue, shield plate, and crust during larval development. In order to be more clear and visual, small partners can look at the schematic diagram of the snail's abdominal cavity torsion (marked A, B, C in the figure) to explain why this phenomenon occurs from an evolutionary point of view. One benefit of the twist is that the body can more easily, quickly and completely indent into the snail shell. Of course, for slugs, due to the degradation of the shell, this twist seems to have no practical choice advantage!
Reproductive foramen
The vast majority of the land-based species of gastropods are hermaphrodites, which means that there are many options for mating and succession. Some can be self-sufficient and some can choose to mate. Mating also has many ways, some have a clear division of labor, male and female are clear; others exchange sperm equally, and both sides are conceived at the same time.
Among them, the mating process of leopard slugs is the most breathtaking: the two protagonists will climb the same tree, suspend themselves in the air with slime, and they shake their bodies in mid-air, protruding from the right side of the "neck" and their genitals are intertwined with each other. In addition, some species of slugs will have a strange scene of one male's genitals being swallowed by the other after mating.
mucus
Since it is called a slug, it is naturally sticky. This mucus is very important for slugs. In addition to the traces mentioned above and the use of "hanging wea" stunts, mucus also has a moisturizing function. There is also a neuroplegic toxin in the mucus that can be used as a defensive weapon.
Finally, four colorful slugs from different continents are dedicated to everyone. Have you all seen them?