Arthroskulus

## Arthroskulus circumcaudus

Status: LC

Timespan: R.77 - Present

Habitat: Shallow Sea

Distribution: Temperate Seas of the Southern Hemisphere

Niche: Minor Predator

Nutritional Value: 28

Size: 6cm

Predecessor: Roharasra wotupiowui

Classification: Roharasridae, Codowecoidea, Aquamusculidia

Latest Mutations: Spiracles, Fan-Tail

Info: Although never far from the seabed, this animal can swim by the use of its fan-tail and it uses this to scour and hunt the surface for its adversary; the larger Regemsitula occisor. However, it has no buoyancy control and so soon must return to the floor and rest.

Description: The top of the blue, cylindrical body is protected by a tough exoskeleton made out of chitin. Some of the armour has formed a fan-shape protruding from the rear, which can be moved up and down by muscle. Also, the armour behind the head contains a spiracle, allowing oxygen through it. Underneath the armour, the animal has a hydrostatic skeleton composed of strong, longitudinal muscles, which seem to be slightly more powerful than those of its predecessors. At the front, the characteristic sharp beak protrudes from a proboscis. There are four pinhole eyes, but none of them look up; two are at the front, and two are on the sides. A muscular siphon at the rear propels out water. Inside their body, they have a simple gut leading to an anus, a stomach containing digestive carnivorous bacteria, a nerve network and small bunch of ganglia, and an open circulatory system filled with blue-green hemacoel. Anti-freeze proteins flow through the hemacoel.

Previous Mutations: Bitter Chemicals, Chemoreceptors, Proboscis, Hydrostatic Muscle Fins (2 vertical near centre of body) (L), Sharp Beak, Digestive Carnivorous Enzymes, Bigger, Blue Pigmentation, Open Circulatory System, Glittery Scales (L), Anti-Freeze Proteins, Hyponome, Cup Eyes (L), Hydrostatic Skeleton, Pinhole Eyes, Exoskeleton Shield, Stronger Muscles

Discoverer: StealthStyle

## Arthroskulus pelagus

Timespan: R.89 - R.126 (Cinisian to Untrustolithic Stage of the Atroxian)

Habitat: Temperate Shallows, Temperate Upper Ocean, Polar Upper Ocean

Distribution: Southern Hemisphere

Niche: Predator

Size: 7.5cm (length)

Nutritional Worth: 30.3

Predecessor: Arthroskulus circumcaudus

Classification: Roharasrinae (sf), Codowecoiidae (f), Probocephala (o), Cylindrea (c), Bilateria (p)

Perception: Blurry vision with no depth perception on either side, blurry front vision with depth perception.

Latest Mutations: Swim Bladder

Info: With a swim bladder allowing Arthroskulus pelagus to control its buoyancy, this species could not only remain around the surface of shallow seas, but also survive out in the open ocean. It hunted worms. It went extinct when Stellingus acridon evolved with strong, crushing jaws, and meant only the better defended Periphractax survived.

Anatomy: The top of the blue, cylindrical body is protected by a tough exoskeleton made out of chitin. Some of the armour has formed a fan-shape protruding from the rear, which can be moved up and down by muscle. Also, the armour behind the head contains a spiracle, allowing oxygen through it. Underneath the armour, the animal has a hydrostatic skeleton composed of strong, longitudinal muscles, which seem to be slightly more powerful than those of its predecessors. At the front, the characteristic sharp beak protrudes from a proboscis. There are four pinhole eyes, but none of them look up; two are at the front, and two are on the sides. A muscular siphon at the rear propels out water. Inside their body, they have a simple gut leading to an anus, a stomach containing digestive carnivorous bacteria, a nerve network and small bunch of ganglia, and an open circulatory system filled with blue-green hemacoel. There is also a swim bladder, unconnected to the gut. Anti-freeze proteins flow through the hemacoel.

Behaviour: This species is capable of processing information gathered from sense receptors and using that to form a picture of its surroundings. It can then respond to stimuli. It also has basic reasoning.

Cause of Extinction: Overpredated

Discoverer: StealthStyle