Scraping the web; first steps towards a comprehensive understanding of global arachnid trade

In recent years exotic pets have become increasingly popular, and amongst that we have seen growth in the trade of arachnids. While monitoring the trade and transport of small vertebrates such as reptiles and amphibians presents a challenge, the monitoring of arachnid trade is harder due to limited knowledge of arachnid species distributions.

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Dimensions of wildlife trade

Wildlife trade is a global threat to biodiversity, and whilst illegal trade has gained increasing attention in recent years, less attention is given to legal trade. As a consequence of this lack of scrutiny, thousands of species may be vulnerable as a consequence of unmonitored and under-regulated trade

 CITES is the UN convention responsible for monitoring and regulating the trade of wildlife, with a mission to prevent species being threatened by unsustainable trade. However, for many “low value” species few regulations exist meaning these species are frequently overlooked. For many smaller taxa we need to gather a basic understanding of what is being traded and from where, before we can assess any of the potential impacts.

The need for more information is particularly acute for invertebrates. Their small body-size makes trading and concealing them easy, while also making identifying species hard. Fluid taxonomy means species names are changing, while new species are rapidly being described. All these factors feed into make regulating or monitoring trade very challenging.

Understanding the impacts of trade is made more difficult by the lack of maps for most species, and under 1% of arachnid species have received a Redlist category by the IUCN. Here we develop the first global maps for arachnids, then use this map to show percentages of species in trade as well as what percentage of species are from the wild versus captive bred.

Trade in invertebrates

Whilst over 54,400 arachnids have been described, CITES only regulates the trade of around 40 species, and no analysis has previously been conducted to assess what species are in trade. High rates of species description further exacerbate these trends; for example, over 1,000 new spider species have been described in the last two decades.

After collating a standardised list of arachnids and cross-referencing synonyms, we conducted a systematic search of online arachnid-selling stores. We combined this search effort with the US Fish and Wildlife’s LEMIS database (wildlife imports into the USA), and CITES records to generate a list of 1,264 arachnid species in trade.

UpSet plot of how the three different sources overlapped in terms of species, with an insert showing how the total number of species was split between three major clades. Lower left hand bar chart shows the number of species detected via each source

Some species were only traded under junior synonyms (possibly to escape CITES regulation), and of only 25 species were found in all three repositories. The 1,264 species came from 371 genera, including five Uropygi, 70 scorpion, and 296 spider genera. When only genera with species in trade were considered, 18% of scorpions, 9% of spiders and 11% of Uropygids are in trade, and when we consider the average number of species in trade per genus it equates to of 31.7% in scorpions, 37% in spiders and 28.5% in Uropygi. Thus, for popular genera large numbers of species are being traded.

Understanding the impacts

Gauging the impacts of trade are challenging, as so few species have been assessed by the IUCN. In fact, while a number of Endangered and Critically Endangered species are in trade, a total of 99.34% of spider species, 100% of Uropygi and 99.9% of scorpions have no Redlist assessments from the IUCN; meaning understanding the potential impacts are virtually impossible. Despite this we see up to 600 species in trade per year, with an increase in the number of species in trade from 2000 to present.

a, b and c) show the source based on the origin listed in the LEMIS database. d, e, and f) show the natural distributions of all traded spiders and scorpions based on all data sources, number of species traded are shown in supplements. N.B., The natural distributions are only accurate to the country level, and in some cases represent extrapolation from broadly defined distributions (e.g., a “South American” distribution would be mapped as including all countries in South America).

Almost all of this trade is legal, only 0.034% of the individuals recorded in LEMIS were seized, and of all individuals in trade 70.4% come from the wild. Even for genera such as Pandinus (the scorpion genus that includes the Emperor Scorpion) with over 1 million individuals in trade, the majority of individuals come from the wild, and only Mesobuthus (Vachon 1950) largely came from captive sources (89.2%). Many of these animals come from a small number of countries, including Ghana, Chile and China; thus, regulations to understand trade must also acknowledge those patterns.

Other dimensions of trade

With high rates of description in arachnids it is not surprising that almost 200 of the species described since 2000 are already in trade, which includes 24% of newly described Theraphosids (that contains many tarantula species). However, in addition many species have a colour or locality linked to the genera name, and on the forums we detected over 100 consistently used localities or colours that may denote undescribed species. In addition, we found 32 different colours associated with arachnid genera.

Different languages also have different markets, with most languages having species only found in trade in that language. Yet unlike our analysis of amphibians and reptiles, keywords were much more challenging for arachnids, thus many further species may also be being traded, especially using social media (e.g., Facebook, Instagram).

Managing trade

Whilst it may seem that as invertebrates arachnids could be regarded as fast breeding and wide ranging, as many invertebrates are, this is not the case for many popular arachnid species in trade. Instead, these species share traits with taxa acknowledged as most vulnerable –long lives, slow breeding, small distributions.

Here we show that many species of arachnid are vulnerable to trade, with examples of very high levels of trade and most individuals originating from the wild. Understanding the dynamics of trade are challenging, particularly with markets using tools like private messages on social media, and thus avoiding any scrutiny.

It is incontrovertible that trade poses a risk to many arachnid species, the precise extent of that risk is difficult to assess without grater monitoring efforts. Without further efforts to manage trade we may see the loss of species (including those not formally described) from the wild. Given the ease of trade of invertebrates managing trade may be challenging. Working with traders to prevent imports wherever possible may be the only way to prevent the current levels of imports of wild individuals, and to better trace origins. Renewed efforts to Redlist and assess under-studied arachnids which may be at risk would help fill critical data gaps and better contextual the impact the arachnid trade is having on wild populations.

Additionally this, like all our work is a product of collaboration from all co-authors, working towards a better understanding of wildlife trade in overlooked taxa to highlight the need for further research, and better regulation.

Alice C. Hughes

Prof, Xishuangbanna Tropical Botanical Garden