Phylum Arthropoda - Subphylum Chelicerata

The most notable characteristic of the phylum Arthropoda is the presence of jointed appendages. A second major characteristic is an exoskeleton. Unlike the cuticles seen in nematodes and tardigrades, the exoskeleton of an arthropod is made primarily of chitin and can be reinforced by the process of biomineralization (the addition of tough minerals and hardened proteins). The anatomy of arthropods divides the body into three main tagma. These tagma include the head, thorax, and the abdomen. In some cases two or more tagma can be fused. When the head and thorax are fused it forms a cephalothorax. When the thorax and the abdomen are fused it is called a trunk.

The subphylum Chelicerata includes spiders, scorpions, mites, ticks, and horseshoe carbs and is named for distinct modified appendage near the mouth called the chelicera. In scorpions and spiders the chelicera have modified into fangs. The second set of appendages is known as the pedipalp. This appendage primarily aids in handling food and mating. After the pedipalps, the chelicerates have four pairs of walking legs. Anatomically chelicerates have a cephalothorax and abdomen. In the abdomen the chelicerates have a specialized respiratory structures known as book gills (aquatic) or book lungs (terrestrial). 

In the first picture you can clearly see the spider’s pedipalps near its head. In the second picture you can all six pairs of appendages of the tick.


4/19/2017         Phidippus otiosus - Adult Female,   SUCH A BEAUTY!!!!

Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynes )
Family Salticidae (Jumping Spiders)
Genus Phidippus
No Taxon (otiosus group)
Species otiosus (Phidippus otiosus)

Other Common Names
Canopy Jumping Spider

Synonyms and other taxonomic changes
See the World Spider Catalog.

Edwards (1) considers this to be part of a species group, but the taxonomy is not clear.

Explanation of Names
Author of species is Hentz, 1846. Species name otiosus is a Latin adjective for free, at leisure (1).

Body length 8-12 mm (male), 12-18 mm (female)

Carapace dark brown with white hairs along the sides. Abdomen is brown above with distinctive pattern in orangish. Chelicerae of both male and female irridescent, usually green, but sometimes purple (2).

Keys for recognizing specimens of Phidippus regius, P. otiosus and P. audax are described in:
Edwards G.B. 1981. The regal jumping spider Phidippus regius (Araneae: Salticidae). Ent. Circ., Florida Dept. Agric. Consumers Service, Gainesville, 223: 1-3, 4 f. (PDF) (HTML)

All information from BugGuide

vedajuno  asked:

Trilobites are pretty much a staple of paleontology and yet they're almost never talked about. What can you tell me about them?

Trilobites were one of the first major groups of animals to establish themselves on the planet Earth, but they’ve never really gotten their due - and their story isn’t a particularly happy one

 Trilobites are classified in their own unique subphylum of Arthropoda, the group that includes modern-day insects, arachnids, crustaceans, and myriapods.  None of these animals are descended from trilobites, who have no direct descendants alive today.  (The modern-day horseshoe crab, while sometimes mistaken for a descendant of trilobites, is actually more closely related to spiders.)

Some of Earth’s earliest known animals, trilobites originated in the Early Cambrian, some 540 million years ago.  The first known trilobites show all the features of later specimens, indicating that even earlier transitional forms exist, but have not yet been discovered.

The trilobites are named for their “three lobes” - the left, right, and central sections into which the thorax of the exoskeleton is divided.  Like modern-day insects, trilobites were divided into three distinct parts - the cephalon (or “head”), the thorax, and the pygidium, a fused segment that may or may not have borne legs.

Wait, they had legs?

I genuinely never knew this.  I thought the “lobes” were how they got around, that they kind of crept around on the ground by wiggling their– oh my God.  This is mind-blowing.  And look, at the top you can see preserved antennae!  I never knew they had those, either!

Holy crap, you can even see the outlines of the legs on the specimen preserved at the bottom!  Am I the only one who never knew this?  Was I the only person who was imagining trilobites wrong his whole life?

Well, regardless, the vast majority of trilobite fossils are shells discarded after molting, composed of only the larger pieces that would have stuck together for a while after such a process.  I guess it’s understandable that I had such a plebeian understanding of trilobites for so long.

Almost all trilobites had large and complex eyes - some of the first to develop in animals.  They likely had very good eyesight, allowing them to spot predators on the approach - or their own prey.

Trilobites inhabited a wide variety of lifestyles.  Some were bottom-dwelling crawlers who scavenged from fallen carcasses; others filter-fed from the silt; still others were predators; and others were active swimmers who fed on plankton.  Some of them, like Phacops rana, defended themselves from predators by rolling into balls of impenetrable armor; others developed more elaborate defenses, like the “trident” of Walliserops trifurcatus.

You might recognize some of the examples in the above list as the roles and adaptations taken on today by crustaceans, the dominant group of marine arthropods in our modern seas.  You might also remember that earlier in this post, I said that trilobites have no living descendants.  That’s not a coincidence.

Trilobites survived through the Cambrian, Ordovician, and Silurian, undergoing explosions of diversity and dominating the prehistoric seas.  Then, the Devonian mass extinction occurred.  It’s uncertain why this extinction occurred, but a great deal of Earth’s life was wiped out, including every order of trilobite - except one.  The order Proetida managed to struggle on into the Carboniferous, but their foothold was already lost; other groups of arthropods quickly filled all the niches that trilobites had abandoned, and the trilobites were completely extinct by the end of the Permian period.

While the trilobites may be long extinct, their strange and alien anatomy still fascinates paleontologists today - even if the public may not be as enthused.  I think it has a great deal to do with the fact that there are just so damn many trilobite species, most of which are pretty indistinguishable at first glance.  However, as you can see from my reaction above, there’s still a lot to learn about these ancient arthropods - and a lot of it may be right under our noses, waiting for us to see it.

How To Make Your Forever Burrow (Even If You Haven’t Found It Yet)

The travelling life can be fun and rewarding, but pretty much every single chelicerate I have ever met has expressed a desire for some sort of “forever-ness” associated with the places that they temporarily reside. From the sea-dwelling Yunnanolimulus luopingensis brought ashore by the tides, the ancient Eurypterus remipes whose records are elusive, to my wonderful cousin Mongolarachne jurassica whose elegant webs have become a symbol of my family for many generations, they’ve always been able to find a semplance of permanence in their ever-changing lives.

So, without further ado, here are my steps to finding your home away from home!

1) Find some comfortable substrate

Something fairly soft, with small grains that use can dig in is desirable. If you’re like me, then a place that you can make a substanially sized burrow that won’t fall apart is important. Pro tip: regardless of what others may say, having a roof made of a log or a large, flat rock is not shameful!

Alternatively, if you find a pre-existing burrow that appears to have been deserted, or has amenable company, then you might be able to use it as a home. Some amphibians have been known to cohabitate with folks of our kind, and are actually very great neighbors, according to a source in the international silk!

2) Check the environment of constant, persistent dangers

There are a variety of haards that can be around your burrow without directly harming you, but some things carry higher risks. For example, a pesky cycad plant whose berries might drop and squish you is probably less dangerous than large vertebrates who like to dig nearby. Unstable ground that may fall apart beneath your tarsi is less likely to directly affect you than constant flooding from the nearby river system. If the danger is clear, immediate, omnipresent, and/or likely to be undeterred by the barring of fangs, then you might want to change locations.

3) Decorate!

Decorations in the home, while not necessary, can make a simple home inthe ground the most comfortable place to be. Making web mats for sleeping and resting is a good idea and keeping your waste in a corner away from everything else can help declutter your humble abode. Some of you may want to build a door, which is 100% okay! You don’t have to keep everything out in the open all the time, it’s good to have privacy sometimes, especially during the very fragile parts of our life cycles.

4) Connect to the outside world with international silk!

While still a new innovation, the international silk has a lot of amazing resources on it! You can find out about nearby migration patterns of large vertebrates, check on the weather, order take-out, and even stay in contact with distant relatives. (I assume that anyone reading this is at least aware of the international silk, since this is housed on one of its numerous networks.)

In conclusion, the most important aspects of having a forever burrow lies in stability and safety. The extra comforts of Mesozoic living are totally up to your druthers, of course, but you may find them wonderful to have in your forever burrow.

I hope this guide is helpful to you young slings out there who are thinking of settling! And even if you’re not thinking of settling, these are good tips to have when looking for temporary places to wait out the cold season. Have fun, stay safe, and keep on exploring!

-Rosa 🕷️


Scorpiones, Scorpio, Scorpion…

It’s hard to get a good picture of a scorpion - they’ve just got so much going on. Here, at least, are four images that show some key features: chelicerate mouth-parts, claws (chela) like an unrelated lobster, and tail with a sting segment (telson) and sting (aculeus). Fun creatures…

Scorpions have been on our little planet for an awful long time with the earliest evidence, fossils from the Silurian, around 450 million years ago, long before vertebrates began their land invasion. Some of these were real beasts up to about one metre (three feet) long, unlike today’s well over 1000 species which are usually less than 10 cm (3 in) long. Thankfully.

Here the images show two species and there’s an obvious difference in two of the images that clearly differentiates them. Know what it is?

Scorpions are one of the Many Little ancient Things.


7/4/2016                         Southern Black Widow

                                       A Beautiful Southern Belle !

Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynes )
Family Theridiidae (Cobweb Spiders)
Genus Latrodectus (Widow Spiders)
Species mactans (Southern Black Widow)
Other Common Names
Black Widow - The L. mactans is often considered the original “Black Widow”.
“The Hourglass Spider” because of the red hourglass shaped mark on the female’s abdomen.
“The Shoe Button Spider” due to the form of the spider’s jet-black abdomen.
lat"ro-dek’t[schwa]s mac'·tans
Explanation of Names
See the Latrodectus guide page for the etymology of Latrodectus.
Adult Female:
    Approximately 8-13 mm (~½ inch) in body length.
    With legs extended, the female measures about 25-35 mm (1 inch - 1 ½ inches).

Adult Male:
    Approximately half the size of the female, around 4-6 mm (¼ inch) in body length.
    With legs extended, the male measures 12-18 mm (½ inch - 2/3 inch).Identification
The southern black widow is one of the most common of the native widow spiders. It is the epitome of the classic widow spider, occurring in all the normal widow spider habitats. Female: The adult female black widow spider has a glossy jet black color all over, including body and legs. The only red marks are the bright red hourglass mark on the underside of the abdomen, and a red spot just behind and above the spinnerets. The hourglass marking consists of two connected red triangles on the underside. Note, however, that the hourglass color may range from yellowish to various shades of orange or red. If the hourglass marking is not connected (e.g. - two distinct, non-touching triangles), it is most likely the northern cousin (L. variolus) of the southern black widow (L. mactans).Males: Adult males are harmless, is 3-5 mm long with an elongated abdomen. The male’s legs are larger than the female’s and each joint is orange brown in the middle and black on the ends. On the sides of the male’s abdomen there are four pairs of red and white stripes. Immatures: Newly hatched spiderlings are predominately white or yellowish-white, gradually acquiring more black and varying amounts of red and white with each molt. Juveniles of both sexes resemble the male and are harmless.Web
The web is typically a 3-dimensional, unorganized mass of silk spun in a dark crevice or corner. The web is sticky, and very strong. If the web is active (in use), the female will be in or very near the web.
It ranges as far north as southern New York, as far south as Florida, and as far west as Texas, Oklahoma, and Kansas. (L. mactans has been found in California, possibly indicating that it can be found in any southern state.) The Southern black widow spider also occurs throughout all four deserts of the American southwest. In addition, Latrodectus mactans has been found in parts of southern Canada.
Outdoors, black widow spider webs are usually built in woodpiles, rubble piles, under stones, in hollow stumps, and in rodent burrows. These spiders commonly occur in outbuildings such as privies, sheds, and garages. Indoors, they prefer undisturbed, cluttered areas in basements and crawl spaces. It is also associated with littered areas, with dumps of large cities, with garages, and storage sheds.
They typically prey on a variety of insects, but occasionally they do feed upon wood lice, diplopods, chilopods and other arachnids. When the prey is entangled by the web, L. mactans quickly comes out of its retreat, punctures and poisons its prey(1) The poison takes about 10 minutes to take effect, meanwhile the prey is held tight by the spider(1). When movements of the prey cease, digestive enzymes are released into the wound(1). The black widow spider then carries its prey back to its retreat before feeding(1). Latrodectus mactans is exclusively carnivorous and antagonistic. Ordinarily it feeds on insects; however, it also consumes wood lice, diplopods, chilopods and other arachnids. Usually, the black widow spider enswathes prey caught in its snare, bites it, and later drags it to its hub, or retreat, to be eaten. Latrodectus mactans inflicts a small wound on its prey, uses its cheliceral teeth to mash it up, pours digestive enzymes on the prey; and sucks up the resulting food. The whole digestion process takes place outside the spider’s body.
Life Cycle
Mating takes place in spring or summer. Black widow spiders reproduce sexually where the male inserts his palpus into the female’s spermathecal openings. The notion that female always eat the male after mating is incorrect! Females have been observed killing and eating the male after mating; however, a large majority of males do escape, especially when he doesn’t remain around the web after mating, and the female is already well-fed.The female lays eggs onto a web where they are camouflaged and guarded. A female black widow spider can produce nine egg sacs in one summer, each containing about 400 eggs . Usually, eggs incubate for 20-30 days, but more than 12 rarely survive through this process, due to cannibalism. It takes two to four months for black widow spiders to mature. The female live on for 180 days after maturing, while a male only lives on for another 90 days. Copulation among Latrodectus mactans is unique. A mature male spins a small “sperm web” and deposits a small quantity of semen on it. He then charges his palps with the sperm, abandons his habitat, and spends considerable effort to locate a female of his species. Once the female black widow spider has been located, courtship begins. The male vibrates the threads of the female’s snare to be sure she is the right species, for her to recognize him as a mate, and to make her receptive to mating. Mating takes place when the male inserts his papal organs into the spermathecal openings of the female. The spermatozoa are released onto the eggs. The female black widow spider’s egg sac is globular shaped (pear-shaped), and are about 1/3 to ½-inch diameter. Sacs are white at first, later turning tan or gray. The eggs are laid onto a small web and are covered with more silk until they are completely surrounded by an egg sac or cocoon. This egg sac is then camouflaged, guarded (while suspended in the web), or carried by the female. Within the egg sac, the eggs hatch and spiderlings (juveniles) emerge. The spiderlings hatch and molt (shed their skin) one time while inside the egg sac. They then disperse by ballooning—extruding silk threads and being transported by air currents. Their growth to maturity requires 2 to 4 months depending on the availability of prey. Spiderlings molt several times before reaching maturity. In addition, the female Latrodectus mactans can store a lifetime supply of sperm to fertilize all the eggs she will ever produce.

axew  asked:

Hey there, I know we have never talked before but I got a request and I have to make a gifset with all the crustaceans-like pokemon in pokemon amie so I asked my followers if they know about crustacean and stuff and someone told me that you would probably know about that... Like, I know Krabby and Kingler are but I'm not sure about Clauncher and Crustle even thought Crustle has 'CRUST' on its name haha so yeah I was wondering if you could explain/help with that c: Sorry about my messy english.

Hey there! I’m always happy to talk about this kind of stuff :D

Crustaceans are a huge huge HUGE group within the arthropods and include animals such as crabs, lobsters, crayfish, shrimps, prawns, and krill, as well as some other animals such as barnacles, sea monkeys (brine shrimp) and copepods (like plankton from spongebob)

Essentially, if it has a segmented shell, lots of legs, and lives in the sea, then it’s probably a crustacean (there are some exceptions, and I’ll come to that in a moment)

The following pokémon are based on crustaceans:

  • Krabby and Kingler (Crabs)
  • Dwebble and Crustle (Hermit Crabs)
  • Corphish and Crawdaunt (Crayfish)
  • Clauncher and Clawitizer (Snapping Shrimp)
  • Binacle and Barbacle (Barnacles) 

Now, the exceptions are found within fossil types. Kabuto and Kabutops are based on horseshoe crabs, however, the name horseshoe crab is misleading because horseshoe crabs are NOT crabs and NOT crustaceans. They are actually in the same group as spiders and scorpions, the chelicerates. So, Kabuto and Kabutops are not crustaceans.

Also, Anorith and Armaldo may look like crustaceans, but again, they are not. They are based on the anomalocarids, a very ancient arthropod group which is long extinct. Anorith and Armaldo are not crustaceans.

I hope that helps! :)

anonymous asked:

do spiders hatch as larva or as little bitty spiders?

They hatch as little bitty spiders!!! 


Larvae are typically a crustacean and insect thing. Arachnids and other chelicerates develop directly, myriapods (centipedes and millipedes) to this too.