Good times to celebrate the diversity of Amblypygi
For as long as I can remember, I have been fascinated by arachnids. Their high diversity, which includes a variety of morphological and behavioral adaptations, is impressive. It might be surprising though that my favorite arachnid group is not spiders, but a relatively small and not-so-diverse order: whip spiders (Amblypygi).
I find it amusing that despite my obsession with Amblypygi, I have not yet written anything about them. This website had a gallery of whip spider photos since day one, but I guess I have been waiting for a good opportunity to mention them on the blog, and there is no better time than right now. A recent publication by my colleagues, describing eight new species of whip spiders found in Brazil, has given this group the much-deserved public attention.
Despite their common name (see footnote †) and general appearance, whip spiders are very different from spiders. They cannot spin silk and therefore have no webs. Their first pair of legs has evolved into long, antennae-like sensory organs, which are used for navigation, detection and manipulation of prey, and social communication. It is ironic that what makes whip spiders so visually appealing to some people (myself included), is the same thing that makes them terrifying for other people: the raptorial pedipalps. Enlarged and armed with strong spines, the pedipalps are used as a catching basket for grabbing and impaling prey. They are also used in mating and fighting rituals. The long, spiny “grabbers” make many people cringe in fear at the sight of a whip spider. But make no mistake: these animals are completely harmless to us. They do not have venom, they cannot sting and never bite, and they will do whatever they can to avoid confrontation with a human. It is therefore unfortunate that whip spiders are often if not always used to provoke feelings of fear and disgust, as seen in TV programs such as “Fear Factor” and movies like “Harry Potter” (see footnote ‡).
For a shy animal, whip spiders sure pack a lot of character. This is something I will address in several future posts. But newly discovered species of whip spiders are always a cause for a celebration. The new paper puts Brazil in competition with Mexico for the title ‘Country with the highest diversity of Amblypygi’ (Brazil wins. For now). One of the possible explanations for the high diversity is the large continental area within the borders of each country, following a classic principle in Ecology that says species richness increases with area. Under the same principle, the smaller neighboring countries are expected to have less species, and this is indeed what we are seeing. Or is it? There might be another reason involved. Because the small order Amblypygi is of no economical and medical importance it is often understudied, so it is very possible that the low amblypygid diversity seen in other countries reflects a lack of research or difficulties in sampling. A similar trend can be found for other groups of organisms sharing the same attributes. It all points to a problem: basic natural history and taxonomic research is becoming less common and receives fewer support, while our conservation efforts aim higher every year. This creates a conflict – how can you protect something if you do not know about its existence? And indeed, the authors of the paper discuss the issue of conservation. The newly discovered whip spiders may already be endangered due to habitat destruction by humans. Nevertheless, their formal description gives them a valid status, and together with other native plants and animals in need of protection, this serves as an incentive for conservation of their natural habitat.
† There is a bit of a confusion around the common name for Amblypygi, as several different names exist. I prefer to call them amblypygids, referring to the scientific name of the group, but if I am forced to use a common name I go with whip spiders. One other frequently used common name is tailless-whip scorpions, which refers to their tailed relatives, the whip scorpions or vinegaroons, members of order Thelyphonida (formerly Uropygi). I completely disagree with the use of tailless whip scorpions as a name for Amblypygi. A large taxonomic group cannot be defined by something it does not have, unless this character is found by default in all other related groups. If you disagree, please consider why humans are not called “tailless monkeys”.
‡ One example in particular that I find infuriating is a series of videos recently turned viral, showing a person literally abusing whip spiders to the point that the animal has no choice but to attack using its pedipalps. Because of my deep interest in amblypygids these sickening videos have been forwarded to me multiple times by friends who thought I might like them. Interestingly, the person who made these videos actually loves arthropods, yet he seems to be unaware that his videos are spreading hate and misinformation towards these remarkable arachnids, not to mention the pointless abuse and stress of wild-caught animals (I have never gone after someone with the goal of publicly shaming them and will not mention any names; those who have seen the videos know the guy and what I am talking about).
A very nice post and great shots, as usual. But I would (semi-seriously) dispute the complete harmlessness of amblypygids – bigger species can pinch really hard, easily drawing blood. They are not dangerous, but man, they can be painful.
“Amblypygids”is also my favorite name but perhaps we should use “bluntbutts”, a literal translation from Greek, to make it easier to remember?
You are right, of course. My intention was to say that like most arthropods, whip spiders will not cause injury without being provoked. However, if they are forcibly grabbed by hand, the long spines can puncture the skin and may even break off. I even had one Heterophrynus specimen biting my fingers using its chelicerae, a very unusual behavior, but again it was completely my fault for catching it.
I love it when a “cephalic” appendage evolves a role in defense while a “thoracic” appendage becomes a sensory structure. It goes to show that evolution has no regard for consistency, haha.
Very interesting perspective. I understand what you mean, however be cautious with this terminology because in arachnids the cephalothorax is a single unit. The pedipalps are used more in prey capture and during mating rather than for defense. In this regard their function is almost identical to that in scorpions, pseudoscorpions, schizomids and vinegaroons. The antenniform legs, on the other hand, are quite unique in Amblypygi.