Who is the youngest?

Most of us know that blue whales of the species Balaenoptera musculus are the largest animals living on the planet today. But few people know about the smallest inhabitants of our planet. Although there is always the possibility of discovering new species that we did not know before, scientists say they have difficulty imagining an animal smaller than this. myxozoan, a microscopic invertebrate creature related to jellyfish.

Beth Okamura of London’s Natural History Museum says myxozoans are the smallest animals on Earth because Many species in this group have only one cell in adults..

We all go through small stages at some point in our life cycle, but when we mature we become complex, multicellular animals. This does not apply to myxozoans. When they mature, they are still single-celled.
– says Okamura.

Adult myxozoans can be as small as 0.02 millimeters (20 micrometers) in diameter. According to the University of Hawaii, this is 100 times smaller than a grain of sand.

The subkingdom Myxozoa has evolved a simple form corresponding to the parasite life cycle. Most myxozoan species produce infectious waterborne spores. Cells from these spores penetrate and develop into both vertebrate hosts such as fish and invertebrate hosts such as annelid worms.

For example, some myxozoans infect the gallbladders of Amazonian fish and “grow” into worm-like creatures that resemble multicellular nematodes but have a single-celled body.

Although some myxozoans cause disease in their hosts, most are harmless. This harmlessness, combined with their small size, means that scientists often overlook these tiny creatures. There are thousands of myxozoa species living all over the world.

competitors

According to a study published in 2012 in the journal Mammal Review, the title of smallest mammal was shared with 5 centimeters tall. Etruscan mouse (Suncus etruscus) and bumblebee bat (Craseonycteris thonglongyai) is 2.9 to 3.3 centimeters in length. However, these bats also have a wingspan of about 15 centimeters, so they are much wider than shrews in flight.

smallest vertebrates miniature frogsSome of them do not exceed two centimeters in length. Mirco Sole, a professor of zoology at Santa Cruz State University in Brazil, called the frog Brachycephalus pulex the smallest known vertebrate in a study published in February 2024 in the journal Zoologica Scripta.

The smallest known vertebrate, Brachycephalus pulex, on a coin / Photo: Renato Gaiga

Mature females of Brachycephalus pulex have an average length of only 8.15 millimeters, while males are even smaller at 7.1 millimeters. These are small enough to fit on a human fingernail.

This tiny species is found in just two mountains in Brazil’s eastern Bahia state and lives in leaf litter near rivers, feeding mostly on ticks.