# Thai Forest Scorpion (Heterometrus)

[![Heterometrus_spinifer_(Ehrenberg,_1828)_Asian_Forest_Scorpion_(6246043808).jpg](https://ned.apes.org.uk/uploads/images/gallery/2023-09/scaled-1680-/7vjFa5DhKxbVZiaT-heterometrus-spinifer-ehrenberg-1828-asian-forest-scorpion-6246043808.jpg)](https://ned.apes.org.uk/uploads/images/gallery/2023-09/7vjFa5DhKxbVZiaT-heterometrus-spinifer-ehrenberg-1828-asian-forest-scorpion-6246043808.jpg)

<table class="infobox biota" id="bkmrk-scientific-classific"><tbody><tr><th colspan="2">[Scientific classification](https://en.wikipedia.org/wiki/Taxonomy_(biology) "Taxonomy (biology)")<span class="plainlinks">[![Edit this classification](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/OOjs_UI_icon_edit-ltr.svg/15px-OOjs_UI_icon_edit-ltr.svg.png)](https://en.wikipedia.org/wiki/Template:Taxonomy/Heterometrus "Edit this classification")</span></th></tr><tr><td>Domain:</td><td>[Eukaryota](https://en.wikipedia.org/wiki/Eukaryote "Eukaryote")</td></tr><tr><td>Kingdom:</td><td>[Animalia](https://en.wikipedia.org/wiki/Animal "Animal")</td></tr><tr><td>Phylum:</td><td>[Arthropoda](https://en.wikipedia.org/wiki/Arthropod "Arthropod")</td></tr><tr><td>Subphylum:</td><td>[Chelicerata](https://en.wikipedia.org/wiki/Chelicerata "Chelicerata")</td></tr><tr><td>Class:</td><td>[Arachnida](https://en.wikipedia.org/wiki/Arachnid "Arachnid")</td></tr><tr><td>Order:</td><td>[Scorpiones](https://en.wikipedia.org/wiki/Scorpion "Scorpion")</td></tr><tr><td>Family:</td><td>[Scorpionidae](https://en.wikipedia.org/wiki/Scorpionidae "Scorpionidae")</td></tr><tr><td>Genus:</td><td><a class="mw-selflink selflink">*Heterometrus*</a>  
<small>[Ehrenberg](https://en.wikipedia.org/wiki/Christian_Gottfried_Ehrenberg "Christian Gottfried Ehrenberg"), 1828</small></td></tr></tbody></table>

***Heterometrus***, whose members are also known by the collective [vernacular name](https://en.wikipedia.org/wiki/Vernacular_name "Vernacular name") **giant forest scorpions**, is a [genus](https://en.wikipedia.org/wiki/Genus "Genus") of [scorpions](https://en.wikipedia.org/wiki/Scorpiones "Scorpiones") belonging to the family [Scorpionidae](https://en.wikipedia.org/wiki/Scorpionidae "Scorpionidae"). It is distributed widely across [tropical](https://en.wikipedia.org/wiki/Tropical "Tropical") and [subtropical](https://en.wikipedia.org/wiki/Subtropical "Subtropical") [southeastern Asia](https://en.wikipedia.org/wiki/Southeastern_Asia "Southeastern Asia"), including [Indonesia](https://en.wikipedia.org/wiki/Indonesia "Indonesia"), [Brunei](https://en.wikipedia.org/wiki/Brunei "Brunei"), [Malaysia](https://en.wikipedia.org/wiki/Malaysia "Malaysia"), [Myanmar](https://en.wikipedia.org/wiki/Myanmar "Myanmar"), [Philippines](https://en.wikipedia.org/wiki/Philippines "Philippines"), [Singapore](https://en.wikipedia.org/wiki/Singapore "Singapore"), [Cambodia](https://en.wikipedia.org/wiki/Cambodia "Cambodia"), [Laos](https://en.wikipedia.org/wiki/Laos "Laos"), [Thailand](https://en.wikipedia.org/wiki/Thailand "Thailand"), [Vietnam](https://en.wikipedia.org/wiki/Vietnam "Vietnam"), [India](https://en.wikipedia.org/wiki/India "India") ([Nicobar Islands](https://en.wikipedia.org/wiki/Nicobar_Islands "Nicobar Islands"), [Andaman Islands](https://en.wikipedia.org/wiki/Andaman_Islands "Andaman Islands")), and [China](https://en.wikipedia.org/wiki/China "China") ([Hainan](https://en.wikipedia.org/wiki/Hainan "Hainan")).<sup class="reference" id="bkmrk-%5B2%5D">[\[2\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-kovarik2004-2)</sup><sup class="reference" id="bkmrk-%5B3%5D">[\[3\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-:0-3)</sup> It is notable for containing some of the largest living [species](https://en.wikipedia.org/wiki/Species "Species") of scorpions.

## <span class="mw-headline" id="bkmrk-taxonomy-1">Taxonomy</span>

The genus was introduced by [C.G. Ehrenberg](https://en.wikipedia.org/wiki/Christian_Ehrenberg "Christian Ehrenberg") (in Hemprich &amp; Ehrenberg, 1828), originally as a [subgenus](https://en.wikipedia.org/wiki/Subgenus "Subgenus") of the genus *[Buthus](https://en.wikipedia.org/wiki/Buthus "Buthus")*.<sup class="reference" id="bkmrk-%5B4%5D">[\[4\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-hemprich&ehrenberg1828-4)</sup> It was elevated to genus rank by [F. Karsch](https://en.wikipedia.org/wiki/Ferdinand_Karsch "Ferdinand Karsch") in 1879.<sup class="reference" id="bkmrk-%5B1%5D">[\[1\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-karsch1879-1)</sup> H.W.C. Couzijn (1978, 1981)<sup class="reference" id="bkmrk-%5B5%5D">[\[5\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-couzijn1978-5)</sup><sup class="reference" id="bkmrk-%5B6%5D">[\[6\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-couzijn1981-6)</sup> subdivided the genus into several [subgenera](https://en.wikipedia.org/wiki/Subgenus "Subgenus"), but F. Kovařík (2004)<sup class="reference" id="bkmrk-%5B2%5D-1">[\[2\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-kovarik2004-2)</sup> [synonymized](https://en.wikipedia.org/wiki/Synonym_(taxonomy) "Synonym (taxonomy)") these subgenera with the nominal genus. In 2020 the genus was reviewed by L. Prendini &amp; S. F. Loria, three of the former subgenera were revalidated and elevated to genera and one valid subgenus was elevated to genus rank, species were transferred to appropriate genera, resulting in 28 new combinations.<sup class="reference" id="bkmrk-%5B3%5D-1">[\[3\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-:0-3)</sup>

### <span class="mw-headline" id="bkmrk-diversity-1">Diversity</span>

The content of this genus may vary, depending on the authority. Eight species are known, many of which are quite similar in appearance:<sup class="reference" id="bkmrk-%5B7%5D">[\[7\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-scorpionfiles-7)</sup>

- *[Heterometrus glaucus](https://en.wikipedia.org/w/index.php?title=Heterometrus_glaucus&action=edit&redlink=1 "Heterometrus glaucus (page does not exist)")* <small>(Thorell, 1876)</small>
- *[Heterometrus laevigatus](https://en.wikipedia.org/w/index.php?title=Heterometrus_laevigatus&action=edit&redlink=1 "Heterometrus laevigatus (page does not exist)")* <small>(Thorell, 1876)</small>
- *[Heterometrus laoticus](https://en.wikipedia.org/wiki/Heterometrus_laoticus "Heterometrus laoticus")* <small>Couzijn, 1981</small>
- *[Heterometrus longimanus](https://en.wikipedia.org/wiki/Heterometrus_longimanus "Heterometrus longimanus")* <small>(Herbst, 1800)</small>
- *[Heterometrus petersii](https://en.wikipedia.org/w/index.php?title=Heterometrus_petersii&action=edit&redlink=1 "Heterometrus petersii (page does not exist)")* <small>(Thorell, 1876)</small>
- *[Heterometrus silenus](https://en.wikipedia.org/w/index.php?title=Heterometrus_silenus&action=edit&redlink=1 "Heterometrus silenus (page does not exist)")* <small>(Simon, 1884)</small>
- *[Heterometrus spinifer](https://en.wikipedia.org/wiki/Heterometrus_spinifer "Heterometrus spinifer")* <small>(Ehrenberg, 1828)</small>
- *[Heterometrus thorellii](https://en.wikipedia.org/w/index.php?title=Heterometrus_thorellii&action=edit&redlink=1 "Heterometrus thorellii (page does not exist)")* <small>(Pocock, 1897)</small>

## <span class="mw-headline" id="bkmrk-general-characterist-1">General characteristics</span>

Members of *Heterometrus* are generally large-sized [scorpions](https://en.wikipedia.org/wiki/Scorpion "Scorpion") (100–200 mm or about 4-8 [in](https://en.wikipedia.org/wiki/Inch "Inch") total length). Coloration is dark in most species, often uniformly brown or black, sometimes with a greenish shine, with brighter-colored [telson](https://en.wikipedia.org/wiki/Telson "Telson"), walking legs, and/or [pedipalp](https://en.wikipedia.org/wiki/Pedipalp "Pedipalp") pincers in some species. The scorpions are heavily built with especially powerful and globose pedipalp pionkes, broad [mesosomal](https://en.wikipedia.org/wiki/Mesosoma "Mesosoma") [tergites](https://en.wikipedia.org/wiki/Tergites "Tergites") and a proportionally slender and thin [metasoma](https://en.wikipedia.org/wiki/Metasoma "Metasoma"). The telson is proportionally small and the stinger is often shorter than the vesicle. The [cephalothorax](https://en.wikipedia.org/wiki/Cephalothorax "Cephalothorax") and mesosoma are largely devoid of carinae and granulation and the median eyes are situated in a small, lenticular depression on the cephalothorax. Some species are parthenogenic.<sup class="reference" id="bkmrk-%5B2%5D-2">[\[2\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-kovarik2004-2)</sup><sup class="reference" id="bkmrk-%5B6%5D-1">[\[6\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-couzijn1981-6)</sup>

Orthobothriotaxy type C. Pedipalp femur with three trichobothria and pedipalp patella consists with 19 trichobothria. Pedipalp chela with 26 trichobothria. Retrolateral pedal spurs are absent. Stridulatory organ is located on the opposing surfaces of pedipalp coxa and first leg.<sup class="reference" id="bkmrk-%5B8%5D">[\[8\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-8)</sup>

### <span class="mw-headline" id="bkmrk-toxicity">Toxicity</span><span class="mw-editsection"><span class="mw-editsection-bracket">\[</span>[edit](https://en.wikipedia.org/w/index.php?title=Heterometrus&action=edit&section=4 "Edit section: Toxicity")<span class="mw-editsection-bracket">\]</span></span>

<figure class="mw-default-size mw-halign-right" id="bkmrk-heterometrus-laoticu">[![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/Asian_forest_scorpion_in_Khao_Yai_National_Park.JPG/220px-Asian_forest_scorpion_in_Khao_Yai_National_Park.JPG)](https://en.wikipedia.org/wiki/File:Asian_forest_scorpion_in_Khao_Yai_National_Park.JPG)<figcaption>*[Heterometrus laoticus](https://en.wikipedia.org/wiki/Heterometrus_laoticus "Heterometrus laoticus")* at [Khao Yai National Park](https://en.wikipedia.org/wiki/Khao_Yai_National_Park "Khao Yai National Park"), [Thailand](https://en.wikipedia.org/wiki/Thailand "Thailand")</figcaption></figure>As in other genera of the Scorpionidae, the symptoms from *Heterometrus* envenomations are rather mild and no human fatalities are known.<sup class="reference" id="bkmrk-%5B6%5D-2">[\[6\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-couzijn1981-6)</sup> The sting causes local pain, [inflammation](https://en.wikipedia.org/wiki/Inflammation "Inflammation"), [oedema](https://en.wikipedia.org/wiki/Oedema "Oedema"), swelling, and redness of the skin, lasting for hours to a few days. Plant extracts known in the traditional Thai medicine as natural scorpion venom antidotes are effective as symptomatic treatment of *H. laoticus* stings.<sup class="reference" id="bkmrk-%5B9%5D">[\[9\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-uawonggul&al2006-9)</sup> The [protein](https://en.wikipedia.org/wiki/Protein "Protein") [heteroscorpine-1](https://en.wikipedia.org/wiki/Heteroscorpine "Heteroscorpine") was found the major component of the venom in *H. laoticus*.<sup class="reference" id="bkmrk-%5B10%5D">[\[10\]](https://en.wikipedia.org/wiki/Heterometrus#cite_note-Uawonggol&al2007-10)</sup>

## <span class="mw-headline" id="bkmrk-habitat-for-the-scor-1">Habitat for the scorpion</span>

Species of *Heterometrus* live in vegetated, often forested, [humid](https://en.wikipedia.org/wiki/Humid "Humid") regions with [subtropical](https://en.wikipedia.org/wiki/Subtropical "Subtropical") to [tropical](https://en.wikipedia.org/wiki/Tropical "Tropical") [climates](https://en.wikipedia.org/wiki/Climate "Climate"). As most scorpions, they are predominantly [nocturnal](https://en.wikipedia.org/wiki/Nocturnal "Nocturnal") and hide in [burrows](https://en.wikipedia.org/wiki/Burrow "Burrow"), below logs, and in [leaf litter](https://en.wikipedia.org/wiki/Leaf_litter "Leaf litter").

## <span class="mw-headline" id="bkmrk-in-captivity-1">In captivity</span>

Due to their impressive size, low toxicity, and docile behavior, species of *Heterometrus* are popular pet scorpions. Unlike many other scorpions, they can be kept in pairs or small groups.