British researchers discovered a foot-and-a-half-long fossilized claw of an ancient sea scorpion.

Ancient sea ,was 8 feet long
A fossilized claw suggests that the giant arthropod, extinct for 250 million years, was a dominant predator.

One of its claws might feed an entire family, but this sea creature would be more likely to eat the family.

British researchers said Tuesday that they had discovered a foot-and-a-half-long fossilized claw of an ancient sea scorpion, a species that would have been 8 feet long, making it the largest arthropod ever discovered.

"We knew the sea scorpions were among the largest creepy-crawlies ever, but we didn't realize just how big they could get," said paleontologist Simon J. Braddy of the University of Bristol, the primary author of the report in the journal Biology Letters. The fossil was found in a quarry near Prum, Germany.

Sea scorpions became extinct about 250 million years ago, but they were precursors of modern land-based scorpions. Smaller varieties are common in the fossil record, and evidence suggests that they ventured forth onto land for at least brief forays.

But "there is no way this thing could have crawled out onto land," Braddy said.

"This is simply too spindly. Its legs would break under its own weight."

And what does an 8-foot sea scorpion eat? Pretty much anything it wants to, Braddy said. The creature would have been the dominant predator in its environment, feasting on armored fish, early vertebrates, other varieties of arthropods and even on smaller sea scorpions.

The lack of predation may have been one factor that allowed the scorpions and other ancient species to grow so large, he said. The high oxygen content of the atmosphere then -- 35% compared with 21% today -- also probably was a factor.

But the sea scorpions were doomed. When vertebrates evolved to large sizes, "the tables were turned," Braddy said.

"The only way they could cope was by downsizing and hiding away. That's why all of them today are very small."




scorpion

scorpion is an arthropod with eight legs. It is a member of the Arachnida class and belongs to the order Scorpiones. Spiders, mites and ticks are also found in the Arachnida class. There are approximately 2000 species of scorpions. They are found widely distributed south of 49° N, except New Zealand and Antarctica.

Physical characteristics
The body of a scorpion is divided into two segments: the cephalothorax (also called the prosoma) and the abdomen/opisthosoma. The abdomen consists of the mesosoma and the metasoma.

Cephalothorax/prosoma: the scorpion's “head”, comprising the carapace, eyes, chelicerae (mouth parts), pedipalps (claw) and four pairs of walking legs.

Mesosoma: the abdomen's front half, is made up of six segments. The first segment contains the sexual organs as well as a pair of vestigial and modified appendages forming a structure called the genital operculum. The second segment bears a pair of featherlike sensory organs known as the pectines; the final four segments each contain a pair of book lungs. The mesosoma is armored with chitinous plates, known as tergites on the upper surface and sternites on the lower surface.

Metasoma: the scorpion's tail, comprising six segments (the first tail segment looks like a last mesosoman segment), the last containing the scorpion's anus and bearing the telson (the sting). The telson, in turn, consists of the vesicle, which holds a pair of venom glands and the hypodermic aculeus, the venom-injecting barb.

Cuticle: this makes a tough armor around the body. In some places it is covered with hairs that act like balance organs. An outer layer that makes them fluorescent green under ultraviolet light is called the hyaline layer. Newly molted scorpions do not glow until after their cuticle has hardened. The fluoresent hyaline layer can be intact in fossil rocks that are hundreds of millions of years old.

On rare occasions, scorpions can be born with two metasomata (tails). Two-tailed scorpions are not a different species, but rather a genetic abnormality

The largest scorpion ever is the extinct 2.5 meter Jaekelopterus rhenaniae.

Birth and development
Unlike the majority of Arachnida species, scorpions are viviparous. The young are born one by one, and the brood is carried about on its mother's back until the young have undergone at least one moult. Before the first moult, scorplings cannot survive naturally without the mother, depending on her for protection and to regulate their moisture levels. Especially in species which display more advanced sociability (e.g Pandinus spp.), the young/mother association can continue for an extended period of time. The size of the litter depends on the species and environmental factors, and can range from two to 100+ scorplings.[5]

The young generally resemble their parents. Growth is accomplished by periodical shedding of the exoskeleton (ecdysis). A scorpion's developmental progress is measured in instars (how many moults it has undergone). Scorpions typically require between five and seven moults to reach maturity. Moulting is effected by means of a split in the old exoskeleton which takes place just below the edge of the carapace (at the front of the prosoma). The scorpion then emerges from this split; the pedipalps and legs are first removed from the old exoskeleton, followed eventually by the metasoma. When it emerges, the scorpion’s new exoskeleton is soft, making the scorpion highly vulnerable to attack. The scorpion must constantly stretch while the new exoskeleton hardens to ensure that it can move when the hardening is complete. The process of hardening is called sclerotization. The new exoskeleton does not fluoresce; as sclerotization occurs, the fluorescence gradually returns.







Life and habits
Scorpions have quite variable lifespans and the actual lifespan of most species is not known. The age range appears to be approximately 4-25 years (25 years being the maximum reported life span in the species H. arizonensis).

Scorpions prefer to live in areas where the temperatures range from 20°C to 37°C (68°F to 99°F), but may survive in the temperature range of 14°C to 45°C (57°F to 113°F).[6]

They are nocturnal and fossorial, finding shelter during the day in the relative cool of underground holes or undersides of rocks and coming out at night to hunt and feed. Scorpions exhibit photophobic behavior, primarily to evade destruction by their predators such as birds, centipedes, lizards, mice, possums, and rats.[7]

Scorpions are opportunistic predators of small arthropods and insects. They use their chela (pincers) to catch the prey initially. Depending on the toxicity of their venom and size of their claws, they will then either crush the prey or inject it with neurotoxic venom. This will kill or paralyze the prey so the scorpion can eat it. Scorpions have a relatively unique style of eating using chelicerae, small claw-like structures that protrude from the mouth that are found only in a handful of invertebrates, including spiders and vinegaroons. The chelicerae, which are very sharp, are used to pull small amounts of food off the prey item for digestion. Scorpions can only digest food in a liquid form; any solid matter (fur, exoskeleton, etc) is disposed of by the scorpion.



Fossil record
Scorpions have been found in many fossil records, including coal deposits from the Carboniferous Period and in marine Silurian deposits. They are thought to have existed in some form since about 425–450 million years ago. They are believed to have an oceanic origin, with gills and a claw-like appendage that enabled them to hold onto rocky shores or seaweed.

The eurypterids, marine creatures which lived during the Paleozoic era, share several physical traits with scorpions and are closely related to them. Various species of Eurypterida could grow to be anywhere from 10 cm (4 in) to 3 m (9.75 ft) in length. However, they exhibit anatomical differences marking them off as a group distinct from their Carboniferous and recent descendants. Despite this, some refer to them as "sea scorpions."[8] Their legs are thought to have been short, thick, tapering and to have ended in a single strong claw; it appears that they were well-adapted for maintaining a secure hold upon rocks or seaweed against the wash of waves, like the legs of shore-crab.