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We have no more batches in the tank, so if you have photos, send them along. Thanks.

Today’s final tranche comes from reader Ephraim Heller, which will be in two parts. Ephraim’s captions and IDs are indented, and you can enlarge his photos by clicking on them:

Q: Why do chickens (Gallus gallus domesticus) in Trinidad & Tobago cross the roads?

A: To eat the tarantulas.

During my recent visit to Trinidad and Tobago, a local birding guide explained that one of the reasons people commonly keep free-range chickens in their yards is to eat the tarantulas. This gave me a new respect for these domestic fowl, as I witnessed venomous tarantulas larger than my XXL-size hands, such as this female Trinidad chevron tarantula (Psalmopoeus cambridgei):

Trinidad harbors a diversity of arachnids that rivals anywhere in the Neotropics. On my night walks with my new macro lens I observed spiders (order Araneae) and harvestmen, also known as daddy long legs (order Opiliones). Both arachnids are eight-legged members of the class Arachnida, but they belong to entirely separate orders and are not closely related within that class.

Returning to the Trinidad Chevron tarantula: it constructs silken tube retreats in tree crevices, behind bark, and among epiphytic plants. It also readily adapts to human structures (e.g., tin roofs, metal pipes, and abandoned buildings) making it something of a synanthrope:

Females are large and fast-growing, reaching 18 cm (7 inches) in leg span, with striking chevron-shaped dark markings on the abdomen and green-brown coloration accented by red or orange flashes on the legs. Males are smaller, with a more uniform grey-brown appearance, and can mature in as little as one year. The species is notable for its broad diet: bats, frogs, lizards, grasshoppers, mice, and other insects have all been documented as prey.

Pharmacologically, the Trinidad chevron tarantula is of medical interest. Its venom is the source of psalmotoxin and vanillotoxin – inhibitor cystine knot (ICK) peptides that may have therapeutic applications in stroke treatment.

The pinktoe tarantula (Avicularia avicularia), is the most commonly encountered tarantula in Trinidad and Tobago. This arboreal species is named for the distinctive pink coloration on the tips of its legs in adults:

Adults reach about six inches in leg span. They are ambush predators that construct silken retreats and trip lines in tree canopies, using webbing as both trap and sensor. Unlike most tarantulas, pinktoes can jump short distances (3-4 cm), and their defensive repertoire includes propelling feces at threats, a behavior that, while unglamorous, is effective. Their venom is mild, even by New World tarantula standards. Here’s a closeup from the previous photo focused on the body:

The Giant Fishing Spider (Ancylometes bogotensis) is a semi-aquatic giant. Females reach roughly 26 mm in body length with an impressive leg span, while males are somewhat smaller at about 21 mm. These spiders walk on water using air-trapping hydrophobic hairs on their leg tips, much like water striders. When disturbed, they can dive below the surface and remain submerged for over 20 minutes by breathing air trapped in the hairs surrounding their book lungs. Their diet ranges from aquatic insects to small fish, frogs, lizards, and geckos:

Ancylometes bogotensis is sometimes confused with the infamous Brazilian wandering spider (genus Phoneutria, photo below): both are large, ground-active, nocturnal hunters with similar body plans. The name Phoneutria translates from Greek as “murderer,” and the genus has appeared in the Guinness World Records as containing the world’s most venomous spider. There are eight described species, found primarily in tropical South America with one extending into Central America.

Phoneutria species are best known for their potent neurotoxic venom, their characteristic threat display (raising the first two pairs of legs high to reveal banded leg patterns) and their wandering, non-web-building habits. They famously hide in banana bunches, boots, clothing, and dark shelters, which brings them into frequent contact with humans. Their venom contains a cocktail of neurotoxins, but fatalities are rare with modern medical treatment.

Though Ancylometes and Phoneutria were both historically placed in the family Ctenidae, Ancylometes was transferred to its own family (Ancylometidae) in 2025, reflecting the growing understanding that these semi-aquatic fishing spiders represent a distinct evolutionary lineage:

We now turn to a species of orb-weaver. The golden silk spider (Trichonephila clavipes) is one of the most conspicuous spiders in the Caribbean and Neotropical forests. Sexual dimorphism in this species is extreme: males are tiny (5-9 mm body length) and weigh roughly one-thousandth what a female does. Here is a female:

The silk itself is remarkable. It has a golden hue visible to the naked eye and is the strongest natural fiber known. Researchers have fully annotated the T. clavipes genome, identifying 28 unique silk protein genes. These spiders produce and utilize seven different types of silk. Their large, asymmetric orb webs can exceed a meter in diameter, and in the South Pacific, relatives of Trichonephila spin webs strong enough to be used as fishing nets by indigenous communities:

Ryan Gosling stars in the latest adaptation of an Andy Weir novel, another tale of a lone genius battling to survive in space. Bethan Ackerley thoroughly approves

Figuring out what really counts as a galaxy could give us insights into dark matter and potentially shake up astrophysics, cosmology and particle physics, says columnist Chanda Prescod-Weinstein

The speed at which artificial intelligence is gaining in mathematical ability has taken many by surprise. It is rewriting what it means to be a mathematician

Scientists occasionally have a hard time figuring out whether data they are seeing is an actual physical phenomenon or just a trick of their instrumentation. A new paper in The Planetary Science Journal from Jessica Sunshine and their colleagues at the University of Maryland describes one such confusing scenario. In this case, the researchers noted some fan-like patterns across the surface of Dimorphos, the asteroid hit by NASA’s DART mission, and thought it might be a trick of their camera. But after some image correction, computation, and physical experimentation, they determined the patterns were caused by the first-ever documented cases of material transfer between two asteroids.

An analysis of ancient and modern DNA suggests the extent of convergent evolution in different peoples around the world is even greater than we thought

Scientists studying Mars may have uncovered a brand-new mineral hidden in the planet’s ancient sulfate deposits. By combining laboratory experiments with orbital data, researchers identified an unusual iron sulfate—ferric hydroxysulfate—forming in layered deposits near the massive Valles Marineris canyon system. The mineral likely formed when sulfate-rich deposits left behind by ancient water were later heated by volcanic or geothermal activity, transforming their chemistry.

Cosmic voids may seem like the emptiest places in the universe, stripped of matter, radiation, and even dark matter. But they’re far from nothing. Even in these vast empty regions, the fundamental quantum fields that fill all of space remain, carrying a small but real amount of energy known as vacuum energy, or dark energy. While this energy is overwhelmed by matter in galaxies and clusters, in the deep emptiness of cosmic voids it becomes dominant.

Cosmic voids may seem like the emptiest places in the universe, stripped of matter, radiation, and even dark matter. But they’re far from nothing. Even in these vast empty regions, the fundamental quantum fields that fill all of space remain, carrying a small but real amount of energy known as vacuum energy, or dark energy. While this energy is overwhelmed by matter in galaxies and clusters, in the deep emptiness of cosmic voids it becomes dominant.

An exploration of the validity of the Silurian hypothesis, which posits the existence of a pre-human intelligent race on Earth.

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The bottom line is this: when given the opportunity to prove his real-world prowess, Dr. Vinay Prasad failed.

The post “Vinay Prasad Loves President Trump”. That, Plus 12 Other Thoughts on the End of Dr. Vinay Prasad’s Sabbatical From UCSF first appeared on Science-Based Medicine.

When NASA’s DART spacecraft deliberately crashed into the asteroid moonlet Dimorphos, it did more than change the asteroid’s local orbit — it slightly shifted the path of the entire asteroid pair around the Sun. The impact blasted debris into space, doubling the force of the spacecraft’s hit and nudging the system’s solar orbit by a tiny but measurable amount. It marks the first time humans have altered the trajectory of a celestial object around the Sun. The result strengthens the case for using spacecraft impacts as a future planetary defense strategy.

Scientists have found a way to significantly boost “blue energy,” which generates electricity from the mixing of saltwater and freshwater. By coating nanopores with lipid molecules that create a friction-reducing water layer, they enabled ions to pass through much more efficiently while keeping the process highly selective. Their prototype membrane produced about two to three times more power than current technologies. The discovery could help bring osmotic energy closer to becoming a practical renewable power source.

US-Israeli strikes on oil facilities have caused black rain to fall on Tehran, but the black smoke filling the air is likely to be a bigger health risk

Their species name is well known, but until recently we’ve understood very little for certain about Homo habilis. Columnist Michael Marshall reveals what new fossils are telling us about the hominins that have been considered the first humans

Lunar dust can be a pain - but it’s also literally the ground we will have to traverse if we are ever to have a permanent human settlement on the Moon. In that specific use case, it’s clingy, jagged, staticky properties can actually be an advantage, according to a new paper, recently published in Research from researchers at Beihang University, who analyzed the mechanical properties of samples returned by Chang’e 6 mission to the far side of the Moon.

We’re learning that frailty can quietly arrive decades before old age, with some people in their 30s or 40s unknowingly in a pre-frail state. There are surprising ways to stay strong – and it’s not all about weight training

Taking a multivitamin every day might slightly slow the rate of ageing, but the extent to which this is relevant to our health is unclear

Jupiter's powerful, continuous aurorae dwarf those of Earth. Scientists know that Jupiter's Galilean moons created bright spots on Jupiter's northern aurora. The JWST observed these bright spots and generated infrared spectra of them for the first time. Those observations showed that Io's bright spot is extremely variable in both temperature and density, and researchers want to know why.

Even when the idea of terraforming Mars was originally put forward, the idea was daunting. Changing the environment of an entire planet is not something to do easily. Over the following decades, plenty of scientists and engineers have looked at the problem, and most have come to the same conclusion - we’re not going to be able to make Mars anything like Earth anytime soon. A new paper available in pre-print on arXiv from Slava Turyshev of NASA’s Jet Propulsion Laboratory, is a good explainer as to why.