Like something out of a zombie movie, species that were once thought extinct seem to be rising from the dead.
Between 21 February and 4 March, three notable rediscoveries were announced – the Fernandina Island Galapagos tortoise (Chelonoidis phantasticus), which was last seen in 1906; Wallace’s giant bee (Megachile pluto), which had supposedly disappeared in 1980; and the Formosan clouded leopard (Neofelis nebulosa brachyura), which disappeared after the last sighting in 1983 and was officially declared extinct in 2013.
These rediscoveries suggest we may know very little about some of the world’s rarest species, but they also raise the question of how species are declared extinct in the first place. The International Union for Conservation of Nature Red List collates a global register of threatened species and measures their relative risks of extinction. The Red List has a set of criteria to determine the threat status of a species, which are only listed as “extinct” when “there is no reasonable doubt that the last individual has died”.
According to the Red List, this requires “exhaustive surveys in known and/or expected habitat, at appropriate times… throughout its historic range [which] have failed to record an individual. Surveys should be over a timeframe appropriate to the taxon’s life cycle and life form”.
Given all the evidence – or rather, lack of evidence – that’s needed, it’s surprising that any species is ever declared extinct. The criteria show that to understand whether a species is extinct, we need to know what it was doing in the past.
1/21 Animal with transient anus discovered
A scientist has stumbled upon a creature with a “transient anus” that appears only when it is needed, before vanishing completely. Dr Sidney Tamm of the Marine Biological Laboratory could not initially find any trace of an anus on the species. However, as the animal gets full, a pore opens up to dispose of waste
Steven G Johnson
2/21 Giant bee spotted
Feared extinct, the Wallace’s Giant bee has been spotted for the first time in nearly 40 years. An international team of conservationists spotted the bee, that is four times the size of a typical honeybee, on an expedition to a group of Indonesian Islands
Clay Bolt
3/21 New mammal species found inside crocodile
Fossilised bones digested by crocodiles have revealed the existence of three new mammal species that roamed the Cayman Islands 300 years ago. The bones belonged to two large rodent species and a small shrew-like animal
New Mexico Museum of Natural History
4/21 Fabric that changes according to temperature created
Scientists at the University of Maryland have created a fabric that adapts to heat, expanding to allow more heat to escape the body when warm and compacting to retain more heat when cold
Faye Levine, University of Maryland
5/21 Baby mice tears could be used in pest control
A study from the University of Tokyo has found that the tears of baby mice cause female mice to be less interested in the sexual advances of males
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6/21 Final warning to limit “climate catastrophe”
The Intergovernmental Panel on Climate Change has issued a report which projects the impact of a rise in global temperatures of 1.5 degrees Celsius and warns against a higher increase
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7/21 Nobel prize for evolution chemists
The nobel prize for chemistry has been awarded to three chemists working with evolution. Frances Smith is being awarded the prize for her work on directing the evolution of enzymes, while Gregory Winter and George Smith take the prize for their work on phage display of peptides and antibodies
Getty/AFP
8/21 Nobel prize for laser physicists
The nobel prize for physics has been awarded to three physicists working with lasers. Arthur Ashkin (L) was awarded for his “optical tweezers” which use lasers to grab particles, atoms, viruses and other living cells. Donna Strickland and Gérard Mourou were jointly awarded the prize for developing chirped-pulse amplification of lasers
Reuters/AP
9/21 Discovery of a new species of dinosaur
The Ledumahadi Mafube roamed around 200 million years ago in what is now South Africa. Recently discovered by a team of international scientists, it was the largest land animal of its time, weighing 12 tons and standing at 13 feet. In Sesotho, the South African language of the region in which the dinosaur was discovered, its name means “a giant thunderclap at dawn”
Viktor Radermacher / SWNS
10/21 Birth of a planet
Scientists have witnessed the birth of a planet for the first time ever.
This spectacular image from the SPHERE instrument on ESO’s Very Large Telescope is the first clear image of a planet caught in the very act of formation around the dwarf star PDS 70. The planet stands clearly out, visible as a bright point to the right of the center of the image, which is blacked out by the coronagraph mask used to block the blinding light of the central star.
ESO/A. Müller et al
11/21 New human organ discovered that was previously missed by scientists
Layers long thought to be dense, connective tissue are actually a series of fluid-filled compartments researchers have termed the “interstitium”.
These compartments are found beneath the skin, as well as lining the gut, lungs, blood vessels and muscles, and join together to form a network supported by a mesh of strong, flexible proteins
Getty
12/21 Previously unknown society lived in Amazon rainforest before Europeans arrived, say archaeologists
Working in the Brazilian state of Mato Grosso, a team led by archaeologists at the University of Exeter unearthed hundreds of villages hidden in the depths of the rainforest.
These excavations included evidence of fortifications and mysterious earthworks called geoglyphs
José Iriarte
13/21 One in 10 people have traces of cocaine or heroin on fingerprints, study finds
More than one in 10 people were found to have traces of class A drugs on their fingers by scientists developing a new fingerprint-based drug test.
Using sensitive analysis of the chemical composition of sweat, researchers were able to tell the difference between those who had been directly exposed to heroin and cocaine, and those who had encountered it indirectly.
Getty
14/21 Nasa releases stunning images of Jupiter’s great red spot
The storm bigger than the Earth, has been swhirling for 350 years. The image’s colours have been enhanced after it was sent back to Earth.
Pictures by: Tom Momary
15/21 A 3D reconstruction of an African grey parrot post euthanasia
Included in Wellcome Image Awards, this 3D image of an African grey parrot shows the highly intricate system of blood vessels.
Scott Birch. Wellcome Images
16/21 Baby Hawaiian bobtail squid
Another Wellcome Images Award winner, this time of baby Hawaiian bobtail squid. The black ink sac and light organ in the centre of the squid’s mantle cavity can be clearly seen.
Macroscopic Solutions. Wellcome Images
17/21 Skeletons of 5,000-year-old Chinese ‘giants’ discovered by archaeologists
The people are thought to have been unusually tall and strong. The tallest of the skeletons uncovered measured at 1.9m
YouTube
18/21 Nasa discovers 75,000 mile-wide hole in the Sun
Sunspots are caused by interactions with the Sun’s magnetic field and are cooler areas on the star’s surface.
Nasa
19/21 View(active tab) Apple News Breaking news email Edit Revisions Workflow Clear Cache NewsScience 132 million-year-old dinosaur fossil found at factory in Surrey
Paleontologists Sarah Moore and Jamie Jordan believe they have discovered a Iguanodon dinosaur, a herbivore that was around three metres tall and 10 metres long
Cambridge Photographers/Wienerberger
20/21 Discovering life on Mars is less likely as researchers find toxic chemicals on its surface
The Echus Chasma, one of the largest water source regions on Mars
Getty Images
21/21 An iris clip fitted onto the eye
This images is apart of the Wellcome Images Awards and shows how an artificial intraocular lens is fitted onto the eye. Used for conditions such as myopia and cataracts.
Cambridge University Hospitals NHS FT. Wellcome Images
1/21 Animal with transient anus discovered
A scientist has stumbled upon a creature with a “transient anus” that appears only when it is needed, before vanishing completely. Dr Sidney Tamm of the Marine Biological Laboratory could not initially find any trace of an anus on the species. However, as the animal gets full, a pore opens up to dispose of waste
Steven G Johnson
2/21 Giant bee spotted
Feared extinct, the Wallace’s Giant bee has been spotted for the first time in nearly 40 years. An international team of conservationists spotted the bee, that is four times the size of a typical honeybee, on an expedition to a group of Indonesian Islands
Clay Bolt
3/21 New mammal species found inside crocodile
Fossilised bones digested by crocodiles have revealed the existence of three new mammal species that roamed the Cayman Islands 300 years ago. The bones belonged to two large rodent species and a small shrew-like animal
New Mexico Museum of Natural History
4/21 Fabric that changes according to temperature created
Scientists at the University of Maryland have created a fabric that adapts to heat, expanding to allow more heat to escape the body when warm and compacting to retain more heat when cold
Faye Levine, University of Maryland
5/21 Baby mice tears could be used in pest control
A study from the University of Tokyo has found that the tears of baby mice cause female mice to be less interested in the sexual advances of males
Getty
6/21 Final warning to limit “climate catastrophe”
The Intergovernmental Panel on Climate Change has issued a report which projects the impact of a rise in global temperatures of 1.5 degrees Celsius and warns against a higher increase
Getty
7/21 Nobel prize for evolution chemists
The nobel prize for chemistry has been awarded to three chemists working with evolution. Frances Smith is being awarded the prize for her work on directing the evolution of enzymes, while Gregory Winter and George Smith take the prize for their work on phage display of peptides and antibodies
Getty/AFP
8/21 Nobel prize for laser physicists
The nobel prize for physics has been awarded to three physicists working with lasers. Arthur Ashkin (L) was awarded for his “optical tweezers” which use lasers to grab particles, atoms, viruses and other living cells. Donna Strickland and Gérard Mourou were jointly awarded the prize for developing chirped-pulse amplification of lasers
Reuters/AP
9/21 Discovery of a new species of dinosaur
The Ledumahadi Mafube roamed around 200 million years ago in what is now South Africa. Recently discovered by a team of international scientists, it was the largest land animal of its time, weighing 12 tons and standing at 13 feet. In Sesotho, the South African language of the region in which the dinosaur was discovered, its name means “a giant thunderclap at dawn”
Viktor Radermacher / SWNS
10/21 Birth of a planet
Scientists have witnessed the birth of a planet for the first time ever.
This spectacular image from the SPHERE instrument on ESO’s Very Large Telescope is the first clear image of a planet caught in the very act of formation around the dwarf star PDS 70. The planet stands clearly out, visible as a bright point to the right of the center of the image, which is blacked out by the coronagraph mask used to block the blinding light of the central star.
ESO/A. Müller et al
11/21 New human organ discovered that was previously missed by scientists
Layers long thought to be dense, connective tissue are actually a series of fluid-filled compartments researchers have termed the “interstitium”.
These compartments are found beneath the skin, as well as lining the gut, lungs, blood vessels and muscles, and join together to form a network supported by a mesh of strong, flexible proteins
Getty
12/21 Previously unknown society lived in Amazon rainforest before Europeans arrived, say archaeologists
Working in the Brazilian state of Mato Grosso, a team led by archaeologists at the University of Exeter unearthed hundreds of villages hidden in the depths of the rainforest.
These excavations included evidence of fortifications and mysterious earthworks called geoglyphs
José Iriarte
13/21 One in 10 people have traces of cocaine or heroin on fingerprints, study finds
More than one in 10 people were found to have traces of class A drugs on their fingers by scientists developing a new fingerprint-based drug test.
Using sensitive analysis of the chemical composition of sweat, researchers were able to tell the difference between those who had been directly exposed to heroin and cocaine, and those who had encountered it indirectly.
Getty
14/21 Nasa releases stunning images of Jupiter’s great red spot
The storm bigger than the Earth, has been swhirling for 350 years. The image’s colours have been enhanced after it was sent back to Earth.
Pictures by: Tom Momary
15/21 A 3D reconstruction of an African grey parrot post euthanasia
Included in Wellcome Image Awards, this 3D image of an African grey parrot shows the highly intricate system of blood vessels.
Scott Birch. Wellcome Images
16/21 Baby Hawaiian bobtail squid
Another Wellcome Images Award winner, this time of baby Hawaiian bobtail squid. The black ink sac and light organ in the centre of the squid’s mantle cavity can be clearly seen.
Macroscopic Solutions. Wellcome Images
17/21 Skeletons of 5,000-year-old Chinese ‘giants’ discovered by archaeologists
The people are thought to have been unusually tall and strong. The tallest of the skeletons uncovered measured at 1.9m
YouTube
18/21 Nasa discovers 75,000 mile-wide hole in the Sun
Sunspots are caused by interactions with the Sun’s magnetic field and are cooler areas on the star’s surface.
Nasa
19/21 View(active tab) Apple News Breaking news email Edit Revisions Workflow Clear Cache NewsScience 132 million-year-old dinosaur fossil found at factory in Surrey
Paleontologists Sarah Moore and Jamie Jordan believe they have discovered a Iguanodon dinosaur, a herbivore that was around three metres tall and 10 metres long
Cambridge Photographers/Wienerberger
20/21 Discovering life on Mars is less likely as researchers find toxic chemicals on its surface
The Echus Chasma, one of the largest water source regions on Mars
Getty Images
21/21 An iris clip fitted onto the eye
This images is apart of the Wellcome Images Awards and shows how an artificial intraocular lens is fitted onto the eye. Used for conditions such as myopia and cataracts.
Cambridge University Hospitals NHS FT. Wellcome Images
Sightings at a certain time and in a certain place make up our knowledge of a species’ survival, but when a species becomes rare, sightings are increasingly infrequent so that people start to wonder whether the species still exists.
People often use the time since the last sighting as a measure of likelihood when deciding if a species has died out, but the last sighting is rarely the last individual of the species or the actual date of extinction.
Instead, the species may persist for years without being seen, but the length of time since the last sighting strongly influences assumptions as to whether a species has gone extinct or not.
But what is a sighting? It can come in a variety of forms, from direct observation of a live individual in the flesh or in photographs, indirect evidence such as foot prints, scratches and faeces, and oral accounts from interviews with eyewitnesses.
But these different lines of evidence aren’t all worth the same – a bird in the hand is worth more than a roomful of recollections from people who saw it in the past. Trying to determine what are true sightings and what are false complicates the declaration of extinction.
The idea of a species being “rediscovered” can confuse things further. Rediscovery implies that something was lost or forgotten but the term often gives the impression that a species has returned from the dead – hence the term “lazarus species”. This misinterpretation of lost or forgotten species means the default assumption is extinction for any species that hasn’t been seen for a number of years.
So, what does this mean for the three recently “rediscovered” species?
While a living specimen of the Fernandina Island Galapagos tortoise had not been seen since 1906, indirect observations of tortoise faeces, footprints and tortoise-like bite marks out of prickly pear cacti had been made as recently as 2013.
The uncertainty around the quality of these later observations and the long time since the last living sighting probably contributed to it being declared “critically endangered (possibly extinct)” in 2015. In the natural world, a species is presumed extinct until proven living.
Wallace’s giant bee may not have been recorded in the past 38 years but it was never actually declared extinct according to the IUCN Red List. In fact, for many years it languished under the criteria of “data deficient” and was only recently assessed as “vulnerable”.
So, while this is an exciting find for something that hadn’t been seen for so long, its rediscovery shows how little is known about many rare species in the wild, rather than how scarce they are.
The Formosan clouded leopard, meanwhile, was actually listed as extinct. The last sighting of the species was in 1983, based on interviews with 70 hunters, and extensive camera trapping during the 2000s failed to detect its presence. It was officially declared extinct in 2013.
While the giant tortoise and bee were proclaimed alive after living specimens were found, the clouded leopard’s rediscovery is more uncertain. Based on sightings on two separate occasions by two sets of wildlife rangers, the evidence is compelling. But whether the Formosan clouded leopard has really risen from the dead will require considerably more effort to prove.
David Roberts is a reader in biodiversity conservation at the University of Kent. This article originally appeared on The Conversation
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