Taxonomists (scientists that classify species) describe thousands and thousands of new extant (living) species every year.
Sometimes these are completely new ones that have never been studied by scientists before, and sometimes it’s a case of a species and its subspecies being examined more closely and it is agreed upon that they ought to be separate species (see boxout below).
And paleontologists (scientists studying extinct species from different geological eras) are also describing new species that they’ve studied from bones, fossils, amber and even fossilised dung.
Recent reclassification of species and subspecies:
- News (2021): Analysis of skulls reveals that river dolphins in South Asia are two separate species
- News (2020): Gentoo penguins should be split into four species, rather than four subspecies
- News (2019): Newly described salamander in museum is the world’s largest amphibian
- News (2017): New identity for UK grass snake
- News (2016): Giraffes are not one species, but four
What is a species?
The concept of a species is arguably the most fundamental in biology. It is surprising, then, that it has caused scientists so much head-scratching. Charles Darwin wanted to do away with the concept altogether, considering it to be defining the indefinable.
The most used definition centres on interbreeding, stating that a species is a group within which two individuals can breed to produce fertile offspring.
In general, this definition holds water, but it can lead to surprising groupings. For example, due to climate change, polar bears and grizzly bears have been coming into contact and producing fertile young. Should we consider these bears one species?
The focus on sex also leaves out organisms that reproduce asexually. Other definitions consider ancestry, though where the lines should be drawn is unclear – are we the same species as our water-dwelling ancestors? Further definitions focus on ecology, geography and physiology.
How many species go extinct each day?
This is impossible to answer precisely. New species appear all the time and can go extinct before they’ve even been described, and estimates as to the rates of extinction very enormously. One approach to working it out would be to first take the yearly ‘natural extinction rate’ – the rate at which species would go extinct if we humans weren’t around. This is often stated as one per million (or 0.00001%) per year – but again, opinion on this varies.
Experts now believe that current rates of extinction have soared to between 1,000 and 10,000 times this natural rate. So, take the natural rate as one per million and that brings current rates to between 0.01 and 0.1% per year. There are said to be 1.6 million described species on our planet, but some experts believe there could be as many as 100 million. So, work out the worse- case scenario maths and the daily rate of extinction comes in at 273 species per day.
We are said to be in the midst of a sixth extinction. Unlike previous mass extinction events, which were the result of climatic shifts, geological activity and a very large asteroid, responsibility for the current losses is down to us.
This Q&A originally appeared in BBC Wildlife Magazine, and was answered by Sarah McPherson.
New species described in 2021:
Here we feature a few of the extant species that have been described so far this year, from impressive spiders in Papua New Guinea named after the activist Greta Thunberg to a tiny chameleon in Madagascar. We have also provided links to the taxonomic papers in which the new species have been described.
Frog, Guinea Shield: Synapturanus zombie
This underground-dwelling frog is one of three new Synapturanus species. The call of the male can only be heard during or after heavy rainfall. To find the animals, scientists need to dig them out of the ground using their bare hands (usually getting soaked in the process). It’s this rather eerie scenario that has given rise to the name Synapturanus zombie.
All three frog species are found in an incredibly biodiverse region of South America known as the Guiana Shield. The scientists believe there may be six times as many Synapturanus species than have been described so far.
Ant, Ecuador: Strumigenys ayersthey
When a species is named after a person, convention holds that the name ends in the suffix ae (after females) or i (males). But what if the person being honoured identifies as neither male nor female? The solution, in the case of this trap-jaw ant named after artist Jeremy Ayers, was to use ‘they’ as the suffix.
Just a single specimen has been collected so far, in tropical forest in northern Ecuador. Extensive efforts to find more proved fruitless, suggesting it is very rare. Its spring-loaded jaws may be a specialisation for catching nimble springtails.
Centipede, Japan: Scolopendra alcyona
This huge centipede – 20cm long and 2cm broad – is only the third amphibious species known to science. It comes in blue-legged and yellow-legged varieties, and is named after Alcyone of Greek mythology, who was turned into a kingfisher – an allusion to its colour and proficiency in and out of the water.
S. alcyona is the first new centipede to be described from Japan in 143 years. It is found under rocks near forest streams on the Ryukyu Islands. Several individuals escaped capture by plunging into the water.
Greta spiders, Madagascar and Mayotte: Thunberga
When the huntsman spider genus Thunberga was named last year after a certain Swedish environmentalist, it contained just a single species. Now, it contains 26. Some of the 25 new ‘Greta spiders’ have been named in honour of other inspirational young people, including human rights activist Malala Yousafzai and environmental entrepreneur Boyan Slat.
All 25 new species hail from Madagascar and its tiny neighbour Mayotte. The females of many of these ambush predators bear numerous scars on their bodies, which are thought to be inflicted by the fangs of males as they grasp them during mating.
Snake, Papua New Guinea: Stegonotus aplini
If snakes were hot drinks, Stegonotus aplini would be a latte macchiato. It’s the seamless transition from milk- white to coffee-brown along its length that sets this serpent apart from its closest relatives, which tend to be a uniform shade of grey or brown.
In the region of southern Papua New Guinea where S. aplini hunts on forest floors at night, local people are highly fearful of the species – even though it is apparently harmless to humans. Perhaps this is because of its superficial resemblance to a more distantly related, venomous snake that also occurs in the region.
Chameleon, Madagascar: Brookesia nana
A tiny chameleon the size of a seed could be a contender for the title of the smallest reptile on Earth. The male nano-chameleon (pictured) has a body just 13.5mm long, yet its genitals are one-fifth of its body size, possibly allowing it to mate with the larger female.
An international team of eagle-eyed scientists spied the reptile within degraded montane rainforests in northern Madagascar. Fortunately, its habitat has been placed under protection, but the researchers have recommended that the bijou chameleon is listed as Critically Endangered on the IUCN Red List of Threatened Species.