In­side the great in­sect die-off

Sci­en­tists have iden­ti­fied 2m species of liv­ing things. No one knows how many more are out there, and tens of thousands may be van­ish­ing be­fore we have even had a chance to en­counter them. But some re­searchers are try­ing, finds Ja­cob Mikanowski

The Guardian Weekly - - Weekly Review -

The Earth is ridicu­lously full of life. Four bil­lion years af­ter the ap­pear­ance of the first mi­crobes, 400m years af­ter the emer­gence of the first life on land, 200,000 years af­ter hu­mans ar­rived on this planet, 5,000 years (give or take) af­ter God bid Noah to gather to him­self two of ev­ery creep­ing thing, and 200 years af­ter we started to sys­tem­at­i­cally cat­e­gorise all the world’s liv­ing things, new species are still be­ing dis­cov­ered by the hun­dreds and thousands.

In the world of the sys­tem­atic tax­onomists – those sci­en­tists charged with doc­u­ment­ing this ever-grow­ing on­rush of bi­o­log­i­cal profli­gacy – the first week of Novem­ber 2017 looked like any other. Which is to say, it was ex­tra­or­di­nary. It be­gan with 95 new types of bee­tle from Mada­gas­car. But this was only the be­gin­ning. As the week pro­gressed, it brought forth seven new va­ri­eties of mi­cro­moth from across South Amer­ica, 10 mi­nus­cule spi­ders from Ecuador, and seven South African recluse spi­ders, all of them poi­sonous. A cave-lov­ing crus­tacean from Brazil. Seven types of sub­ter­ranean ear­wig. Four Chi­nese cock­roaches. A noc­tur­nal jel­ly­fish from Ja­pan. A blue-eyed dam­sel­fly from Cam­bo­dia. Thir­teen bris­tle worms from the bot­tom of the ocean – some bul­bous, some hairy, all hideous. Eight North Amer­i­can mites pulled from the feath­ers of Ge­or­gia road­kill. Three black corals from Ber­muda. One An­dean frog, whose bright orange eyes re­minded its dis­cov­er­ers of the In­can sun god Inti.

About 2m species of plants, an­i­mals and fungi are known to sci­ence thus far. No one knows how many are left to dis­cover. Some put it at around

2m, oth­ers at more than 100m. The true scope of the world’s bio­di­ver­sity is one of the big­gest and most in­tractable prob­lems in the sci­ences. There’s no quick fix or cal­cu­la­tion that can solve it, just a steady drip of new ob­ser­va­tions of new bee­tles and new flies, ac­cu­mu­lat­ing to­wards a fath­om­less goal.

But even as thousands of new species are be­ing dis­cov­ered ev­ery year, thousands more seem to be dis­ap­pear­ing, swept away in an eco­log­i­cal catas­tro­phe that has come to be known as the sixth ex­tinc­tion. There have been five such dis­as­ters in the past. The most fa­mous (and re­cent) is the endCre­ta­ceous ex­tinc­tion, the one that killed off the di­nosaurs 66m years ago. The most destruc­tive was the Per­mian, the one that cleared the way for the di­nosaurs 190m years be­fore that.

To know if we are re­ally in the midst of a sixth ex­tinc­tion, sci­en­tists need to es­tab­lish both the rate at which species are cur­rently van­ish­ing, and the rate at which they would go ex­tinct with­out hu­man ac­tiv­ity (known as the “back­ground rate”). In 2015, us­ing a cen­sus of all known ver­te­brates, a team of Amer­i­can and Mex­i­can sci­en­tists ar­gued that an­i­mal species are go­ing ex­tinct “up to 100 times” faster than they would with­out us – a pace of dis­ap­pear­ance on a par with the ex­tinc­tion that took out the di­nosaurs.

But as Terry Er­win, the leg­endary trop­i­cal en­to­mol­o­gist, pointed out to me, th­ese sixth-ex­tinc­tion es­ti­mates are “bi­ased to­wards a very small por­tion of bio­di­ver­sity”. When it comes to in­ver­te­brates – the slugs, crabs, worms, snails, spi­ders, oc­to­puses and, above all, in­sects that make up the bulk of the world’s an­i­mal species – we are guess­ing. “Con­ser­va­tion­ists are do­ing what they can, with­out data on in­sects,” he said.

To re­ally know what’s go­ing on with the state of the world’s bio­di­ver­sity, ecol­o­gists need to start pay­ing more at­ten­tion to the in­ver­te­brates and spend less time on the “cute and cud­dlies” – Er­win’s term for the ver­te­brates. (Years of hear­ing about the won­ders of go­ril­las and hump­back whales can make a staunch bug man re­sent­ful.) Af­ter all, there are far, far more of them than there are of us.

We live in an in­ver­te­brate world. Of all known an­i­mal species, less than 5% have back­bones. About 70% are in­sects. Fewer than one in ev­ery 200 are mam­mals, and a huge pro­por­tion of those are ro­dents. Looked at from the point of view of species diver­sity, we mam­mals are just a hand­ful of mice on a globe full of bee­tles. The great ma­jor­ity of those bee­tles are her­bi­vores na­tive to the trop­ics. So if you re­ally want to un­der­stand the to­tal diver­sity of life on Earth – and the true rate at which it is dis­ap­pear­ing – you need to fig­ure out how many types of bee­tle munch on ev­ery va­ri­ety of trop­i­cal tree.

But be­fore you can count species, you have to name them. That’s where the tax­onomists come in. The idea of species has been no­to­ri­ously hard for bi­ol­o­gists to de­fine, es­pe­cially since or­gan­isms so of­ten ex­ist on a con­tin­uum, be­com­ing harder and harder to dis­tin­guish the closer they are to each other. The most widely ac­cepted def­i­ni­tion comes from the evo­lu­tion­ary bi­ol­o­gist Ernst Mayr, who de­fined species as groups of an­i­mals that breed with one an­other, but not with oth­ers – at least not in the reg­u­lar course of events. (If you force a ze­bra and a don­key to­gether to make a zon­key, you’ve cre­ated one hy­brid, not dis­proved the fact that they are two dif­fer­ent species, since such a mat­ing would not nor­mally oc­cur in na­ture.)

Tax­onomists do not just name in­di­vid­ual species; they also have to fig­ure out how species are re­lated to each other. Over the cen­turies, many sci­en­tists have tried to fit the world’s crea­tures into a co­her­ent sys­tem, with mixed re­sults. Aris­to­tle tried to clas­sify all life forms based on their es­sen­tial traits, and in par­tic­u­lar, the way they moved. Seden­tary an­i­mals gave him the most trou­ble. He seems to have spent a lot of time on the is­land of Les­bos, puz­zling over whether sea anemones and sponges were an­i­mals, plants, or plant-like an­i­mals.

The real revo­lu­tion in tax­on­omy came in the 18th cen­tury, dur­ing the age of En­light­en­ment. It was largely the work of one man, Carl Lin­naeus, who was hailed as the Isaac New­ton of bi­ol­ogy. Lin­naeus was an odd fig­ure to rise to such heights: a bril­liant, head­strong, ego­tis­ti­cal showoff with a prodi­gious knack for re­mem­ber­ing

the sex­ual char­ac­ter­is­tics of plants. He made one ma­jor ex­pe­di­tion – to La­p­land, in Swe­den’s north – but mostly re­lied on the dis­cov­er­ies of oth­ers. He in­spired 17 “apos­tles” to ven­ture into the world in search of spec­i­mens to com­plete his sys­tem. Seven never came home. Based on their col­lec­tive work, he named 7,700 species of plants and 4,400 species of an­i­mals.

Later bi­ol­o­gists found much to quib­ble with in Lin­naeus’s sys­tem. For in­stance, he grouped hedge­hogs and bats to­gether as “fe­ro­cious beasts”, and shrews and hip­pos to­gether as “beasts of bur­den”. Lin­naeus’s last­ing achieve­ment was not in cre­at­ing the groups them­selves, but the sys­tem by which all sub­se­quent species would be named. He decreed that all species should have a two-part name. The first part in­di­cates the genus to which a species be­longs, and the sec­ond part is the species name.

This is a bril­liantly ef­fi­cient sys­tem for both nam­ing and sort­ing. With it, we can tell in an in­stant that we, Homo sapi­ens, are both re­lated to, and dis­tinct from, our evo­lu­tion­ary rel­a­tives Homo erec­tus and Homo ha­bilis. It is also a source of con­sid­er­able fun for tax­onomists. Pres­i­den­tial names – the bushi, oba­mai and don­ald trumpi (a re­mark­ably coiffed moth) – re­li­ably grab head­lines. Less fre­quently, species names in­voke pol­i­tics or re­cent events. A Brazil­ian mayfly re­ceived the species name trage­diae, to com­mem­o­rate the cat­a­strophic col­lapse of a dam in 2015. Tax­onomists are also not above the oc­ca­sional pun or rhyme. Terry Gosliner, an ex­pert on nudi­branchs, or marine sea slugs, once giv­ing the name Kahuna to a species be­long­ing to genus Thu­runna from Hawaii, to make Thu­runna kahuna.

Gosliner found his first nudi­branch while still at high school. Since then he has trav­elled the world in search of them, and has named more than 300 in his 40-year ca­reer. As denizens of co­ral reefs, sea slugs are par­tic­u­larly sen­si­tive to ris­ing sea tem­per­a­tures. Some sci­en­tists think cli­mate change and ocean acid­i­fi­ca­tion might cause reefs to van­ish en­tirely in the next 50 to 100 years. Gosliner tends to be a bit more op­ti­mistic, em­pha­sis­ing the reefs’ abil­ity to bounce back from stress. But while reefs face peril in the seas, an even greater cri­sis could be de­vel­op­ing for in­sects on land – the true di­men­sions of which en­to­mol­o­gists are only be­gin­ning to grap­ple with.

Be­fore en­to­mol­o­gists could pon­der the ter­ri­fy­ing pos­si­bil­ity of an in­sect mass ex­tinc­tion, they first had to come to grips with the true scale of in­sect diver­sity. They are still strug­gling to do that now. But for many, the break­through mo­ment came in 1982, with a brief pa­per pub­lished by a young bee­tle spe­cial­ist – Terry Er­win.

Er­win wanted to fig­ure out how many species of in­sect lived on an av­er­age hectare of rain­for­est in Panama, where he was work­ing. To do this, he cov­ered a sin­gle tree in sheet­ing and “fogged” it, by blast­ing it with in­sec­ti­cide from a de­vice re­sem­bling a leaf­blower. He waited sev­eral hours while dead bugs cas­caded on to the plas­tic sheet­ing he had spread on the ground. He then spent months count­ing and sort­ing them all. What Er­win found was startling: 1,200 species lived on this one tree. More than 100 lived on this par­tic­u­lar tree and nowhere else. Scal­ing this re­sult up, Er­win es­ti­mated that there are 41,000 dif­fer­ent species in ev­ery hectare of rain­for­est, and 30m species world­wide.

This es­ti­mate quickly be­came fa­mous, and con­tro­ver­sial. Er­win is widely re­spected in the field. He has been com­mem­o­rated in the names of 47 species, two gen­era, one sub­fam­ily and one sub­species – a good gauge of re­spect in the en­to­mo­log­i­cal com­mu­nity, where nam­ing a species af­ter your­self is for­bid­den by cus­tom, but not law. Still, many en­to­mol­o­gists are scep­ti­cal about Er­win’s wilder es­ti­mates, and more re­cent stud­ies have tended to re­vise the 30m num­ber down some­what. But Er­win re­mains in­tran­si­gent. “It’s like Wy­att Earp and Billy the Kid, th­ese kids out here tak­ing pot­shots at me. None of them have any data,” he told me re­cently. “They’re just sit­ting in that of­fice throw­ing num­bers around.” He thinks the real num­ber might be as high as 80m, or even 200m – and that a large num­ber of th­ese species are in the process of van­ish­ing with­out any­one be­ing around to even no­tice.

Ev­ery­where, in­ver­te­brates are threat­ened by cli­mate change, com­pe­ti­tion from in­va­sive species and habi­tat loss. In­sect abun­dance seems to be de­clin­ing pre­cip­i­tously, even in places where their habi­tats have not suf­fered no­table new losses. A trou­bling new re­port from Ger­many has shown a 75% plunge in in­sect pop­u­la­tions since 1989, sug­gest­ing that they may be even more im­per­illed than any pre­vi­ous stud­ies sug­gested.

En­to­mol­o­gists have watched this de­cline with grow­ing con­cern. When Brian Fisher, an en­to­mol­o­gist at the Cal­i­for­nia Academy of Sci­ences with a par­tic­u­lar ex­per­tise in ants, ar­rived in Mada­gas­car in 1993, he ex­pected he would be able to de­scribe some new species, but he had no idea of the ex­tent of the riches he would find there. “Ev­ery­thing was new. It was like it was in the 1930s,” Fisher said. In that time, he has iden­ti­fied more than 1,000 new species of ant, in­clud­ing some whose adults feed ex­clu­sively on the blood of their own young, a group he has nick­named the “Drac­ula ants”.

A thou­sand ants is quite a lot, but sci­en­tists have iden­ti­fied 16,000 species – so far. To a layper­son like me, they all seem ba­si­cally alike. Some are brown, some are black, some are cin­na­mon-coloured, but

other than that, they look pretty much like the (in­va­sive, Ar­gen­tine) ants that swarm my kitchen in Cal­i­for­nia ev­ery time it rains. To an ex­pert like Fisher though, they are as dif­fer­ent from one an­other as war­blers are to a birder. Un­der a mi­cro­scope, each ant pos­i­tively bris­tles with iden­ti­fy­ing fea­tures in their flag­el­late hairs, their seg­mented an­ten­nae, and most of all, in their mandibles, which un­der mag­ni­fi­ca­tion look like di­a­bol­i­cal gar­den shears.

In the decades since Fisher started making ex­pe­di­tions to Mada­gas­car, de­for­esta­tion has ac­cel­er­ated, and today only 10% of its vir­gin forests re­main in­tact. Fisher says that “in 50 years I can’t imag­ine any for­est left in Mada­gas­car”. Ac­cord­ing to Wendy Moore, a pro­fes­sor of en­to­mol­ogy at the Univer­sity of Ari­zona, who spe­cialises in ant nest bee­tles, “There is a sense of run­ning out of time. Every­one in the field who is pay­ing at­ten­tion feels that.” Be­cause many in­sects de­pend on a sin­gle plant species for their sur­vival, the dev­as­ta­tion caused by de­for­esta­tion is al­most unimag­in­ably huge.

While we still don’t have a clear idea of what’s hap­pen­ing to in­sects at the species level, we are in the midst of a cri­sis at the pop­u­la­tion level. Put sim­ply, even if many kinds of in­sects are hold­ing on, their over­all num­bers are fall­ing dras­ti­cally. The alarm­ing data from Ger­many, which was based on track­ing the num­ber of fly­ing in­sects cap­tured at a num­ber of sites over 35 years, is one warn­ing sign among many. Ac­cord­ing to es­ti­mates made by Claire Rég­nier of the French Nat­u­ral His­tory Mu­seum in Paris, in the past four cen­turies, as many of 130,000 species of known in­ver­te­brates may have al­ready dis­ap­peared.

Var­i­ous kinds of anec­do­tal ev­i­dence ap­pear to sup­port th­ese ob­ser­va­tions. The en­vi­ron­men­tal jour­nal­ist Michael McCarthy has noted the seem­ing dis­ap­pear­ance of the wind­screen phe­nom­e­non. Once, he writes, “any long au­to­mo­bile jour­ney”, es­pe­cially one un­der­taken in sum­mer, “would re­sult in a car wind­screen that was in­sect-spat­tered”. In re­cent years this phe­nom­e­non seems to have van­ished.

Although in­sec­ti­cides have been blamed for the de­clines in Europe, Er­win thinks the ultimate cul­prit is cli­mate change. The lo­ca­tion he has been ob­serv­ing in Ecuador is pris­tine, vir­gin rain­for­est. “There’s no in­sec­ti­cides, noth­ing at all,” he said. But grad­u­ally, al­most im­per­cep­ti­bly, in the time he has been there, some­thing has changed in the bal­ance of the for­est. Study­ing the data, Er­win and his col­lab­o­ra­tors have found that over the past 35 years, the Ama­zon rain­for­est has been slowly dy­ing out. And if the for­est goes, Er­win tells me, “ev­ery­thing that lives in it will be af­fected”.

If this trend were to con­tinue in­def­i­nitely, the con­se­quences would be dev­as­tat­ing. In­sects have been on Earth 1,000 times longer than hu­mans have. In many ways, they cre­ated the world we live in. They helped call the uni­verse of flow­er­ing plants into be­ing. They are to ter­res­trial food chains what plank­ton is to oceanic ones. With­out in­sects and other land-based arthro­pods, EO Wil­son, the renowned Har­vard en­to­mol­o­gist, and in­ven­tor of so­cio­bi­ol­ogy, es­ti­mates that hu­man­ity would last all of a few months. Af­ter that, most of the am­phib­ians, rep­tiles, birds and mam­mals would go, along with the flow­er­ing plants. The planet would be­come an im­mense com­post heap, cov­ered in shoals of car­casses and dead trees that re­fused to rot. Briefly, fungi would bloom in un­told num­bers. Then, they too would die off. The Earth would re­vert to what it was like in the Sil­urian pe­riod, 440m years ago, when life was just be­gin­ning to colonise the soil – a spongy, si­lent place, filled with mosses and liv­er­worts, wait­ing for the first shrimp brave enough to try its luck on land.

Con­serv­ing in­di­vid­ual in­sect species piece­meal, as is done with most en­dan­gered mam­mals, is ex­tremely dif­fi­cult. Not only are the num­bers mind-bog­gling, but in­sects and other in­ver­te­brates don’t have the same ca­chet. Po­lar bears and hump­back whales are one thing; soft-bod­ied plant bee­tles from the Gaoligong moun­tains of Yun­nan are quite an­other.

Not long ago, I took a trip to the first wildlife refuge es­tab­lished with the ex­press pur­pose of pro­tect­ing an en­dan­gered in­sect, the An­ti­och Dunes Na­tional Wildlife Refuge, about an hour’s drive north-east of Berke­ley, Cal­i­for­nia. The re­serve is small – only 22 hectares, hemmed in on three sides by a chain-link fence, and by the San Joaquin river on the fourth – and, in truth, the Dunes do not daz­zle the eye. The ter­rain re­sem­bles an over­grown plot of land in­tended for de­vel­op­ment at some point in the fu­ture. The day I went, three vul­tures hud­dled around the body of a cat while the tur­bines of a wind farm spun lazily on the op­po­site bank of the river.

Once, how­ever, th­ese dunes were a minia­ture Sa­hara, home to a num­ber of an­i­mals and plants that ex­isted nowhere else. It took decades be­fore that fact be­came ap­par­ent to bi­ol­o­gists, and by then, it was nearly too late. When white set­tlers ar­rived in Cal­i­for­nia, the dunes were seen sim­ply as a source of raw ma­te­ri­als. The dune sand was un­usu­ally well­suited for brick­mak­ing, and be­tween the San Fran­cisco earth­quake of 1906 and the post­war hous­ing boom, most of the sand was mined out and turned into build­ings. Once the dunes were gone, most of the land they for­merly stood on was built up.

It wasn’t un­til the 1960s that bi­ol­o­gists be­gan to re­alise how spe­cial the An­ti­och Dunes were. By that point, only three na­tive

species re­mained. There were two plants – the Con­tra Costa wallflower and the An­ti­och Dunes evening prim­rose – and one in­sect, the Lange’s metal­mark but­ter­fly. The metal­mark but­ter­fly is tiny, with a wing­span about the size of a thumb­nail. A pretty brown-and-orange with white spot­ting, they are weak fly­ers, ca­pa­ble of trav­el­ling a max­i­mum 400 me­tres af­ter they emerge from their chrysalises for seven to nine days ev­ery Au­gust.

Af­ter the Dunes Re­serve was es­tab­lished in 1980, the but­ter­fly en­joyed a brief resur­gence. Today, it is strug­gling. At last count, there were only 67 in­di­vid­u­als in the park. The Lange’s lay their eggs on one plant and one plant only: the naked-stemmed buck­wheat, which is cur­rently be­ing choked out by weeds. The only other pop­u­la­tion of Lange’s is in a cap­tive-breed­ing pro­gramme at Moor­park Col­lege in Simi Val­ley, Cal­i­for­nia. If some­thing should hap­pen to th­ese, it would be the end of the species.

In a bid to save the but­ter­fly, the US Fish and Wildlife Ser­vice has re­cently be­gun a bold ex­per­i­ment in habi­tat restora­tion, cov­er­ing much of the refuge in sand. Spread a me­tre deep, the sand suf­fo­cates in­va­sive plants, al­low­ing the species that orig­i­nally evolved on the dunes to re­claim their lost ground. “If we can bring back the en­vi­ron­ment, we can bring back the but­ter­fly,” wildlife refuge man­ager Don Brubaker told me. The day I vis­ited, his co-worker, refuge spe­cial­ist Louis Ter­razas, spot­ted a hope­ful sign. The sea­son’s first shoots of na­tive prim­rose had just started peek­ing out above the sand. Given time, this rem­nant of a rem­nant might spring back to life.

When I asked Brubaker if his painstak­ing ef­forts on behalf of the Lange’s was worth all the trou­ble, he replied: “Why pro­tect the species? Why not? Be­cause it’s what we do – we’re en­abling the planet to keep func­tion­ing.”

In some ways, the tiny ranges of in­ver­te­brates like the Lange’s metal­mark but­ter­fly make them per­fect tar­gets for pro­tec­tion. Sa­rina Jepsen is the di­rec­tor of en­dan­gered species and aquatic con­ser­va­tion at the Xerces So­ci­ety, a Port­land, Ore­gon-based non­profit fo­cus­ing on in­ver­te­brates. She told me that for in­sects, “of­ten small patches of land can make a huge dif­fer­ence”, un­like what is needed for, say, wolf or tiger con­ser­va­tion. “We don’t nec­es­sar­ily need hun­dreds of thousands of acres to make a dif­fer­ence with th­ese species,” she said. Even so, the amount of work that goes into sav­ing even a sin­gle species can some­times feel over­whelm­ing. It isn’t enough to save one in a lab. You have to res­cue whole en­vi­ron­ments – the prod­ucts of com­plex in­ter­ac­tions be­tween plants, an­i­mals, soil and cli­mate that have built up over mil­len­nia.

At a cer­tain point, it be­comes clear that to even think about ex­tinc­tion in terms of in­di­vid­ual species is to com­mit an er­ror of scale. If en­to­mol­o­gists’ most dire pre­dic­tions come true, the num­ber of species that will go ex­tinct in the com­ing cen­tury will be in the mil­lions, if not the tens of mil­lions. Sav­ing them one at a time is like try­ing to stop a tsunami with a cou­ple of sand­bags.

Like many of the species they study, tax­onomists are presently at risk of be­com­ing a dy­ing breed. Fac­ulty hires, mu­seum posts and govern­ment grants are all de­clin­ing. Fewer stu­dents are drawn to the field as well. All too of­ten, tax­on­omy gets dis­missed as old-fash­ioned and in­tel­lec­tu­ally un­de­mand­ing, the sci­en­tific equiv­a­lent of stamp col­lect­ing. Molec­u­lar bi­ol­ogy, with its con­cern for DNA, pro­teins and chem­i­cal pro­cesses within in­di­vid­ual cells, dom­i­nates cur­ricu­lums and hoovers up grant money. “All the univer­sity cour­ses are ori­ented to­wards it, and so is the fund­ing,” says Terry Er­win.

Mean­while, the new species keep pil­ing up. Al­ready today, as I’m writ­ing, ZooKeys and Zootaxa, two of the largest and most pro­lific tax­o­nomic jour­nals, have an­nounced the dis­cov­ery of a pot­ter wasp from South Amer­ica, a wa­ter scav­enger bee­tle from the Ti­betan plateau, an ere­bid moth, an An­dean scarab bee­tle, two Korean crus­taceans and a whole genus of par­a­sitoid wasps (don’t worry, we’re safe – they prey on aphids), and it isn’t even noon yet.

What to do with this on­rush? Many tax­onomists I spoke to ad­mit that it sim­ply isn’t man­age­able. Brian Fisher con­fessed that many tax­onomists find them­selves awed at some point by “the im­men­sity of what we don’t know”. Ki­pling Will, of the Univer­sity of Cal­i­for­nia, Berke­ley, who has spent two decades study­ing one sub­fam­ily of ground bee­tles, told me, while ges­tur­ing at boxes of sam­ples that had just flown in from Australia: “We do what we can. I have so much un­de­scribed ma­te­rial. It takes decades just to get where we are.” With any species, it takes time to do a proper dis­sec­tion, test their DNA, com­pare them to their near­est rel­a­tives, and com­pile all the in­for­ma­tion nec­es­sary to pub­lish some­thing as new. With so many in­ver­te­brates be­ing found each year, it’s com­mon for them to spend years, or even decades, in a queue wait­ing for their com­ing-out party.

So what to do? And why bother? There are plenty of prac­ti­cal rea­sons to worry about the fate of in­ver­te­brates. They are a vi­tal part of the ecosys­tems that func­tion as the heart, lungs and di­ges­tive sys­tem of our planet. Some might carry, in­side their ex­otic bio­chemistries, cures for any num­ber of dis­eases. Re­cently, chem­i­cals har­vested from sea slugs have been tested in clin­i­cal tri­als in the US for use as cancer-fight­ing drugs. Oth­ers could be used as nat­u­ral al­ter­na­tives to pes­ti­cides. But ul­ti­mately, it’s not cer­tain that any of th­ese will be enough on its own. The an­swer could have more to do with aes­thet­ics, or en­thu­si­asm for the liv­ing world – the qual­ity EO Wil­son named “bio­philia”.

When you ask peo­ple who work in in­ver­te­brate tax­on­omy why they have de­voted their lives to a par­tic­u­lar type of in­sect, snail or clam, the word you hear most of­ten is “beau­ti­ful”. Their eyes light up in front of their cho­sen genus or sub­class. The oc­cu­pants of a case full of slightly iri­des­cent, mostly black bee­tles will be de­scribed as “rather huge and in­cred­i­bly beau­ti­ful”. (Huge is rel­a­tive, too – they are the size of the fi­nal joint of a lit­tle fin­ger.) Sur­rounded by jars full of tiny sea slugs, they will gush about their beauty and the glo­ri­ous va­ri­ety of their colour, shape and be­hav­iour. Amy Berkov, a pro­fes­sor of trop­i­cal ecol­ogy at the City Col­lege of New York who works on wood-bor­ing bee­tles, came to en­to­mol­ogy from a back­ground in art and chose her new field, in part, be­cause “there’s noth­ing more amaz­ing than look­ing at in­sects”. Even the ant spe­cial­ists – gen­er­ally a pretty hard-nosed bunch – will trade Latin names of rare ants with the af­fec­tion you usu­ally hear re­served for old friends.

It’s easy to care about the cute and cud­dlies. Soon we’ll be liv­ing on a planet that has lost its last moun­tain go­rilla, its last leatherback tur­tle. A world with­out tigers or po­lar bears: what a sad place that will be. But to think about the com­ing in­ver­te­brate ex­tinc­tions is to con­front a dif­fer­ent di­men­sion of loss. So much will van­ish be­fore we even knew it was there, be­fore we had even be­gun to un­der­stand it. Species aren’t just names, or points on an evo­lu­tion­ary tree or ab­stract se­quences of DNA. They en­code count­less mil­len­nia of com­plex in­ter­ac­tions be­tween plant and an­i­mal, soil and air. Each species car­ries with it be­hav­iours we have only be­gun to wit­ness, chem­i­cal tricks honed over a mil­lion gen­er­a­tions, whole worlds of mimicry and vi­o­lence, ma­ter­nal care and car­nal ex­u­ber­ance. To know that all this will dis­ap­pear is like watch­ing a li­brary burn with­out be­ing able to pick up a sin­gle book. Our role in this de­struc­tion is a kind of van­dal­ism, against their his­tory, and ours as well.

Take one of the ants I heard dis­cussed with such warmth at the Cal­i­for­nia Academy of Sci­ences. Stru­migenys is a preda­tor, a na­tive of the un­der­growth, and very rare. It was first dis­cov­ered in 1986 by Phil Ward of the Univer­sity of Cal­i­for­nia, Davis. He spot­ted this in­cred­i­bly rare species on a two-hectare patch of woods a few kilo­me­tres from his of­fice. It has never been seen any­where else. Ward thinks there is a rea­son for this. Cal­i­for­nia rivers were once flanked by gi­ant forests of hardy, flood-re­sis­tant, ever­green oaks. Ge­ol­o­gists think th­ese river­ine forests were a fea­ture of the land­scape for at least 20m years. Ac­counts from early set­tlers and ex­plor­ers give an idea of what they might have been like. They write of flocks of geese “black­en­ing the sky”, sal­mon chok­ing the streams and griz­zly bears gath­er­ing un­der the oaks to feed on acorns in troupes of a hun­dred or more.

Today, ex­cept for a few scat­tered patches like the one Ward found in Yolo County, those forests are gone. They were chopped down long ago for fire­wood and ploughed un­der to make way for to­mato farms and al­mond or­chards. The sal­mon, the geese and the griz­zlies have all gone too. Only the ant re­mains. Only it re­mem­bers.

To even think about ex­tinc­tion in terms of in­di­vid­ual species is to com­mit an er­ror of scale

Pho­tos: Alamy; Getty; Rex

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