Our Observation of the Week is this Black Widow (genus Latrodectus) and its American Broad-front Fiddler Crab (tribe Minucini) prey! Seen in the United States by @evan_tree.

“As part of Texas Master Naturalists, I was fortunate enough to visit the East Foundation's El Sauz Ranch in deep south Texas,” says Evan Trees. 

While most of the group was looking up at birds, I was looking down in a very old (and dry) concrete cattle trough and in an enclosed corner I spotted the black widow's web, which I was very surprised to see had trapped a crab. I saw that the spider was still feeding on this particular crab (a type of American Broad-front Fiddler Crab) and there was another wrapped and discarded below in the leaf litter. I later told Texas Parks and Wildlife Dept urban wildlife biologist Sam Kieschnick (@sambiology), who was nearby, and he immediately gave it a precise identification as a Northern Black Widow (Latrodectus variolus).

I believe the crabs must scuttle up from a nearby brackish water pond and get trapped in the enclosure, eventually stumbling into the web to be consumed.

The genus Latrodectus - known as widow spiders, redbacks, and button spiders, among other English names, is one of the world’s most notorious spider groups, as their venom is medically significant to humans. A widow bite causes latrodectism, the symptoms for which include fever chills, and intense muscle pain. It sounds like a truly miserable illness but is rarely fatal, and widow spiders do not seek out humans to bite, they must be provoked and generally given no other option. 

It’s decapodian prey is an unknown species of fiddler crab (family Ocypodidae), and fiddler crabs show up in tropical and temperate areas of the world. They’re fairly terrestrial and can be seen on beaches and sandy areas where the males court females by waving their one large “fiddling” claw. Latrotoxin, as Evan pointed out to me, contains at least one chemical that specifically affects crustaceans, so if the spider is able to get a bite in then the crab can be subdued.

Originally from the US state of Pennsylvania, Evan (above) credits his interest in nature to his family, his rural upbringing and the scouts. He moved to Texas about a decade ago and tells me

I've completely fallen for the incredibly unique and fragile ecosystems here -- karst springs, chalk prairies, vernal pools. I spend a lot of time in the greenbelts, urban creeks and overgrown lots around Austin observing the effects of development on wildlife, what manages to endure in hidden places and how life rebounds in the aftermath of disturbance.

For me, iNaturalist is a lens through which to see all the hidden, incredible things around me. I like to go into “Explore” and find plants or trees nearby that I'm learning about to go out and see in person. And when I see something I don't recognize, after identifying it I like to look through observations by other users to see what the plant looks like in different seasons, under different conditions and at different phases of development. And I'm just now learning more about connecting with and communicating with other users since some more training given by Texas Master Naturalists.

(Photo by Pearl Chen. Some quotes have been lightly edited for clarity.)

- check out this interview with @sambiology from 2017! 

- a birder’s fiddler crab observation in California extended the species’ range by hundreds of kilometers.

- Deep Look has some phenomenal footage of Latrodectus spiders here, as well as some surprising facts about their reproductive behaviors.

Our Observation of the Week is this Sanniostracus carnavalescus snail, seen in Brazil by @nagylafachetti!

Nágyla Fachetti Coser works at Sooretama Biological Reserve, which is “the largest conservation unit in the state of Espírito Santo, with more than 27 thousand hectares of forest,” she tells me. “I have always been interested in nature, but this interest strengthened when I started working here and having closer contact with the forest, which is home to enormous biodiversity, which I love.”

A few weeks ago, Nágyla was helping to monitor one of the reserves trails when she spotted the snail you see above. “I saw it in a tree and at first I hesitated to record it as I already had many records of snails,” she says, “but I later photographed and posted it to iNaturalist.”

Nágyla’s observation is one of only eight observations of the species on iNat, and I reached out to Daniel Cavallari (@danielcavallari), a Brazilian taxonomist who recently coauthored a paper that moved the snail from Leiostracus to the genus Sanniostracus, which he says is “a portmanteau of two lexicons, ‘sannio’ (Latin for ‘harlequin’). and ‘ostrakon’ (Greek for ‘shell’).” 

As far as we know, it is endemic to the Atlantic Forest of southeastern Brazil. While it was described in 2016, the stretch of forest where the species was initially found was deforested to make way for tomato cultivation. This left us concerned about the possible extinction of the species, but other individuals were observed (including here on iNaturalist) later. We were scared, but considering the vulnerability of land snails to climate change and such, it was a well-founded scare! 

“I still don't have training in the environmental area,” says Nágyla (above). “I'm currently taking a technical course on the environment and I'm interested in all groups of living beings. I always try to photograph as many individuals, animals, plants, fungi, and later post them on iNaturalist.”

I use iNaturalist, because this is a platform that brings together nature lovers from all over the planet. through it I can acquire a lot of knowledge, discover the names of species that I photograph and contribute to science and research. I can photograph a rare species, or even one that has not yet been described, and thus attract more researchers to explore the enormous biodiversity of the reserve.

Using iNaturalist has certainly changed my relationship with the natural world. Now I am more attentive to issues of conservation and preservation of nature, I am increasingly willing to see its beauty, even in small details, like tiny animals and fungi, for example.

(Photo of Nágyla by Sheyla Rossi. Nágyla wrote to me in Portuguese. I used Google Translate, and performed some alterations to the quotes for clarity and flow.)

- Daniel also coauthored this paper, which looks at the utility of iNat as a tool when studying tropical mollusks!

- check out two past terrrestrial gastropod observations of the week, one from @souhjiro, and another from @pizzamurderer!

- Sanniostracus carnavalescus belongs to the family Bulimulidae. Take a look at some of the most-faved observations of that taxon!

Our Observation of the Week is this Utricularia kumaonensis bladderwort plant, seen in Nepal by @elizabeth_byers!

“I grew up in the Adirondack Mountains of northern New York state where nature is dramatic and accessible,” says Elizabeth Byers, who’s currently a wetland ecologist in the Appalachian Mountains of West Virginia. “I love the verticality of biodiversity in the mountains, walking upward through different life zones and discovering hidden treasures on cliffs, in deep forests, and in little jeweled wetlands.”

And it’s not just the Appalachians where Elizabeth works, she has a special interest in subalpine and alpine ecosystems of eastern Nepal. Last year, she and her husband Alton spent five months in Kanchenjunga Conservation Area, a roadless part of eastern Nepal, where they studied alpine ecosystems on a Fulbright grant. Even getting to their research area involved walking a week from the nearest road, in canyons along the Tamur River. 

The Tamur River has some impressive riverside cliffs, and the trail snakes up and down the side slopes to circumvent them. There is one spot where a dangerous boardwalk has been built right along the cliff face directly over the rapids of the river, and the river spray washes the seepy moss-covered cliff face (and anyone walking by). For a botanically-minded person, this habitat is the mother lode for Utricularia species, tiny carnivorous plants that grow on wet cliffs where soil is essentially absent. Utricularia, also called bladderworts, derive nitrogen from miniscule insects that are lured into tiny spheres or bladders on the plant’s roots.  The bait is a sweet nectar, and once through the trapdoor there is no escape. Digestive fluids flood the bladder and digest the insect.

So, while carefully navigating the precarious boardwalk over the river, I stopped and braced my feet to search for Utricularia. My gasp of surprise and awe was completely inaudible above the roar of the rapids - there were literally tens of thousands of them in perfect bloom along the cliff face, more than I’ve ever seen in all of my wanderings. Shielding my camera (a Panasonic Lumix DC-ZS70) from the wet spray, I took a bunch of photos and collected a specimen to bring back to the National Herbarium in Kathmandu.

As Elizabeth said, bladderworts grow in wet areas where there isn't much soil - pretty much only the flowers are what stick out. Some, especially in Central and South America, are epiphytic and have large, showy, orchid-like flowers. 

“I've recently completed a field guide (mobile app) to the “Wildflowers of Mount Everest” in Nepal, and I’m working on a book on the “Flowers of Mount Kanchenjunga” with three Nepali colleagues, plus contributing to the upcoming “Primroses of Nepal” book,” says Elizabeth (above, taking the first-ever photograph of the rare Primula ramzanae).

iNaturalist has changed how I collaborate with international colleagues, how I develop restoration tools, and how I teach plant identification classes. It has also allowed me to enrich my life by learning some biota that are not in Plantae. It’s a transformational database and a remarkable community of experts and enthusiasts that is making nature more accessible while so many other forces in the world are distancing us from our roots. Especially in remote areas, it is a key tool for documenting biodiversity.

(Photo of Elizabeth by Alton Byers. Some quotes have been lightly edited.)

- here’s an explanatory video of how a bladderwort’s bladder trap actually works, and some nice footage of one in action.

- check out the most-faved bladderworts on iNat!

We are pleased to announce iNaturalist has joined 1% for the Planet as an environmental partner! This partnership offers a new way for iNaturalist to expand its impact by reaching more businesses involved in the environmental movement.

1% for the Planet is an accountability partner for businesses that are ready to reject business as usual and give back to environmental partners making a difference around the globe. Started in 2002 by Yvon Chouinard, founder of Patagonia, and Craig Mathews, founder of Blue Ribbon Flies, their members have given hundreds of millions of dollars to environmental partners to date.

To date, 5400+ business partners have given more than $540 million USD to environmental partners around the world.

“The intent of 1% for the Planet is to help fund these diverse environmental organizations so that collectively they can be a more powerful source in solving the world’s problems,” writes Yvon Chouinard, co-founder of 1% for the Planet.

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