All spiders in the Portia genus are fascinating because of how much they accomplish with so little. They’re all tiny little jumping spiders, mostly under one centimeter, so they have tiny little brains.
Most Portia spiders have a brain of only 600,000 neurons, which is physically much smaller than the head of a pin. This forces them to think rather slowly from our point of view, but compared to their prey, they’re devastatingly brilliant.
For example, many jumping spiders are know to take detours when stalking prey. Portia spiders are notable for taking very long detours that break line of sight, which means they must remember and predict where the prey will be when they arrive.
When hunting sedentary web-building spiders, which usually have poor vision, a Portia spider will mimic a bit of leaf or bark to get into attack range. They only move forward during light breezes that shake the web enough to hide their footsteps. If the target moves to defend itself, Portia will disengage, retreat, and try again.
If they can’t get a good approach, they have also been recorded mimicking the vibrations of a trapped insect, or a male spider’s mating dance, to lure the prey spider into attack range. One Portia Fimbriata, the fringed jumping spider, was observed using trial and error to vibrate a target web for three days, repeating any pattern that caused the prey spider to move closer.
In places where other spiders aren’t common enough to be reliable prey, Portia adapts. They’ve been witnessed scavenging and even consuming nectar from flowers. They also innovate new tactics to hunt insects. For example, many insects freeze and stand motionless to avoid predators. Portia spiders counter this by guessing where the prey is and jumping nearby, which often scares the target into breaking cover and running. Then Portia can spot it and resume the normal detour-and-ambush routine.
The population native to Queensland, Australia is particularly inventive. They’re known to drop down on target spiders from above, a tactic called “swooping”. While all other Portia gladly jump into target spider webs, the Queensland orb weaver Argiope Appensa discourages them by shaking the web violently, which disrupts their normal techniques. Swooping counters this defense.
They also use a unique walking gait, slow and robotic, when hunting other saltacid jumping spiders with large forward-facing eyes. They freeze and depend on their natural camouflage whenever the target looks directly at them, so we suspect they prey may not even recognize them as living creatures. Portia rarely uses this “cryptic stalking” technique against any other prey.
Portia Africanus appeared to be a comparatively bad hunter at first glance, but that was in lab testing with 1v1 combat. In the wild, this spider hunts in packs.
Yes, really. They form social groups that hunt cooperatively and sometimes share prey. Groups of mixed ages and sexes will gang up outside the nest of a target spider. They prevent the target from entering or leaving and surround them until one of the Portia, usually a juvenile, manages to lunge forward and bite.
What animal looks like it would screm the loudest
the bare-throated bellbird is so loud that it can cause permanent damage to human hearing at close range!
and they absolutely look like it.
today’s funky frog of the day is: pseudophryne corroboree! commonly known as the southern coroboree frog, they are one of australia’s most endangered species, only found in kosciuszko national park. these frogs are able to produce their own toxin, an alkaloid called pseudophrynamine, instead of obtaining it by diet like most poisonous frogs. because of this, they have no natural predators, but they are threatened by climate change and habitat disturbance. there are reportedly less than 200 of these frogs left.
this surprisingly white yellow-throated toucan was spotted in costa rica within its native habitat. the bird’s odd appearance is due to leucism, a genetic condition that leads to an absence of pigmentation. birds with plumage in abnormal colors are prone to increased predation and weak feathers due to lack of melanin.
@elodieunderglass A leucistic toucan for you!
HII WHO WANTS TO SEE SOME IRIDESCENT SLIME MOLDS
Lamproderma species. i love when stuff on earth looks like it belongs on some other made-up planet
Mollusk shells persist long after the death of the soft-bodied animals whose secretions formed the protective covers. These sturdy remains can inform us about species living in an area at that time. Many mollusks occur in specific habitats and during certain time periods in Earth’s history. When we find mollusks in sediment with dinosaur bones, for example, we receive a clue about the geologic age and habitat in which those dinosaurs lived. When mollusks first appear in an area, deposits containing their shells allow us to estimate when events in Earth’s history occurred, including archaeological events, or even relatively recent construction projects.
This morning as I walked across the Panther Hollow bridge near Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, I noticed clam shells in the concrete of the sidewalk. What can the presence of these clam shells tell me about how long that sidewalk has been there?
Top: Clam shell in sidewalk on Panther Hollow Bridge. Bottom: Close-up of clam shell, inside view. Scale in mm.
Concrete is a mixture of cement with sand and gravel. When sand and gravel are taken from rivers, this natural resource sometimes contains clam shells. I believe the clam shells in this sidewalk were scooped up along with the sand and gravel to make the concrete. Then after the sidewalk was poured, but before it fully hardened, the clam shells floated to the upper surface.
As an aside, information about comparative densities is instructive here. Two common crystal forms of calcium carbonate are calcite and aragonite, which have different densities (calcite 2.71g/cc, aragonite 2.93). Most mollusks form shells of aragonite. However, shells are not pure aragonite, containing small amounts of protein and other substances, so clam shells can have densities around 2.5-2.6. In comparison, the density of quartz, which makes up much of the sand used in making concrete, is 2.65. The clam shells are slightly lighter than the sand, which probably explains why they floated up to the sidewalk surface.
I identified these clam shells as Corbicula fluminea (common name: the Asian clam). They have the characteristic shape and size, the outside has strong regular growth ribs, and on the inside, the lateral teeth bear minute serrations. This species was first recorded in North America in British Columbia about 1924. As an invasive species, it has spread, through human activity, to at least 46 US States.
Top: Outside view of clam showing strong ribs. Middle: Partly broken clam, inside view showing external rib impressions in concrete below. Bottom: Close-up of clam’s lateral teeth showing minute serrations. Scale in mm.
When did the species appear in southwestern Pennsylvania? There is a record of Corbicula fluminea in 1979 from the Ohio River just downstream from Pittsburgh and another in Greene County, southwestern Pennsylvania from 1981. Museum records of this species became more common after about 1993, suggesting that the clam probably became more common about then.
Corbicula fluminea collected in 1993 from Loyalhanna Creek, Southwestern Pennsylvania. Top: inside of shell. Bottom: outside of shell showing strong ribs. Scale in mm.
Consequently, I conclude that the Corbicula fluminea-containing concrete sidewalk on the bridge next to Carnegie Museum must have been poured after the late 1970s, and possibly after 1993, when the clam became abundant in freshwater of western Pennsylvania, the region where Pittsburgh is located.
Museum collections provide useful information about when non-native species arrived in an area. Now you know that one of the many uses of mollusks is estimating ages of things.
Although some people might think of clams as an abstract concept, here is an example of clams in the concrete!
Timothy A. Pearce, PhD, is the head of the mollusks section at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.