When we think of a snail, the first thing that comes to mind is not sharp teeth. But we have to change this vision because these molluscs show us terrible teeth when we look at them under a microscope. Snails have a kind of toothed tongue called a radula, with which they lick the surface of food. They are even capable of crushing rocks. These mini-teeth wear down quickly, so they grow several rows each day. The radular apparatus is made up of two parts: the odontophore (cartilage base) and the radula itself. An individual can have up to 100,000 teeth on its radula, which are normally composed of chitin and some minerals.
These rows of teeth are very different between species, so it is an aspect to hold on to for identifications. Above are two scanning electron micrographs of two different radulae. The first corresponds to Spekia zonata , a freshwater snail from Lake Tanganyika, Africa. In the second case we have a land snail from East Africa.
In general, the shape, arrangement, composition and number of teeth is an adaptation to the diet of the species in question. There are gastropods that even use their radulae to hunt other gastropods or bivalves. In some cases there is even the existence of a single harpoon-shaped radular tooth.
A new species of snail discovered in Spain is no exception, since, as we have seen, the radula serves as the identity card of the species. In the case of the discovered Spanish snail, they are several overlapping rows of short but pointed “teeth”. They were found in caves, which seems incredible, since these mollusks are only a few millimeters in size. If we add that they are also transparent, it borders on the category of a miracle. But it is not like that, because a group of four researchers knew what they had in hand. It was not, therefore, fortuitous.
The discovery has been reported in the journal Organisms Diversity & Evolution, under the title Molecular investigation and description of Iberozospeum n. gen., including the description of one new species (Eupulmonata, Ellobioidea, Carychiidae) .
“The underground areas of the Cantabrian-Pyrenean region of northern Spain are home to a rich diversity of Zospeum,” the article begins. The authors analyzed different populations of Zospeum from caves in northern Spain. Zospeum is a genus of small-sized land snails whose habitat is exclusively hypogeal, that is, underground.
“We managed to collect 57 gastropod populations from various caves,” said zoologist Adrienne Jochum of the Senkengberg Research Institute, Germany, who is one of the study’s co-authors. The other authors are Jannette Kneubühler (University of Bern, Switzerland), Carlos E. Prieto (Department of Zoology and Animal Cell Biology, Faculty of Science and Technology, University of the Basque Country) and Eike Neubert (University of Bern, Switzerland).
Using mitochondrial and nuclear markers, they have demonstrated the existence of a new species, which they have named Iberozospeum costulatum. “A new species corroborated by genetic and morphological characters is described,” the Abstract concludes. This new species has been found in the El Pedreo Mine (Vizcaya), Valdebeci Cave (Vizcaya) and Cuvias Negras Cave (Cantabria).
But it is also that other species that were known fall within the same genus, so they propose a new genus, Iberozospeum. The new species, Iberozospeum costulatum , has teeth ending in two points, which differentiates it from other local species, which have smaller and more abundant teeth. The genus owes its name to the Iberian origin and to its close relatives, Zospeum, also known from the Alps and the Balkans.
“This radula is used for grazing and sifting through cave mud for food particles,” Jochum continues.
The researchers suspect that the diversity of snails of this type in the Cantabrian Sea is due to the fact that the area became a refuge for them during the Pleistocene ice age. They probably evolved separately due to differences in the substrates of the caves in which they were found. For example, the density of mud. Somehow the snails’ “teeth” are like the beaks of Darwin’s finches.
“The teeth of species in some habitats are significantly harder than those in others, which shows how strongly the mechanical properties of the radula are correlated with the properties of the substrate and food,” said zoologist Wencke Krings of the University of Hamburg.
Iberospeum costulatum has a “medium-sized” shell, measuring between 1.24 and 1.55 millimeters. The shell of I. costolatum is transparent. In fact, the different species of the close genus Zospeum share similar sizes and transparent shells. As mentioned above, some species of Zospeum have been included in the genus Zospeum: Iberozospeum schaufussi , Iberozospeum bellesi , Iberozospeum biscaiense , Iberozospeum vasconicum , Iberozospeum zaldivarae , Iberozospeum percostulatum , Iberozospeum praetermissum and Iberozospeum gittenbergeri . As we can see, there are a couple more references to the area they inhabit, in the cases of I. biscaiense and I. vasconicum .
“Iberozospeum differs from Zospeum by the generally smaller shell (average 1.2mm),” the article concludes. “Radular teeth are smaller and more numerous per row.”
Adapted from Newly Discovered Transparent Cave Snail Has Long Rows of Intimidatingly Spikey Teeth.
Original article: Molecular investigation and description of Iberozospeum n. gen., including the description of one new species (Eupulmonata, Ellobioidea, Carychiidae).
