Biology of Planet Atar

Due to the similarity of problems faced by lifeforms from Atar to those from Earth, the lifeforms of Atar bare some resemblance to the lifeforms from Earth. Atar has animalian analogues to most Eartian animals both extant and extinct, including, but by no means limited to, arthropods (terrestrial and marine), sponges, cnidarians, worms, mollusks, fish, reptiles, mammals, and lissamphibians. A similar position exists for plant-like organisms, and also microorganisms. This article is a general overview of the biology of Atar.

Flora
Broadleaf land plants are essentially identical on both planets. Conifers are unknown on Atar, their roles being occupied by the leafless protiods. Similarly, the grasses are unique to Earth, but their roles in controlling moisture and erosion and in feeding and sheltering wildlife are taken over by the long-leafed dicotic amienes. Atar has no true flowers, but some groups bare structures that are functionally similar to flowers and become fruit, however, they do not look like a typical Earth flower.

Fauna
Animal and microbial life on Atar is quite abundant and diverse, especially in the seas. Many of them have organs that are functionally or even visually similar to those from Earth. They are, on average, smaller than Eartian animals. The following Eartian phyla are represented by Atarian analogues:

Microorganisms
Atar has a great abundance of microorganisms. They are fairly identical to microorganisms on Earth, and like microorganisms from Earth and elsewhere, can potentially be pathogenic to other life forms. They are important as decomposers, pathogens, and symbionic microfauna.

Invertabrates
Analogues exist on Atar for jellyfish, polyps, worms and worm-like taxa, bivalves, gastropods, and cephalopods, and brachiopods. Others have no known Eartian analogues, and would appear quite bizzare to a human. Although crinoid and urchin analogues are known, no Atarian lifeforms are analogous to sea stars.

Arthropod-like lifeforms are plentiful on Atar and are found in every environment, from the highest mountain peaks to the deepest ocean trenches. Many are unlike anything known from Earth.

Fish
Fish-like organisms thrive in Atar's waters and include some of the largest animals on Atar, such as gwarfish. They live in freshwater, brackish, and marine environments. Only a very few can survive in brine. They superficially resemble fish and fulfill some of the same roles as on Earth. Gills differ from fish gills in their construction, with many possessing additional external gills, especially in hypoxic conditions. Most possess swim bladders and crescent-shaped sensory patches on the lateral surfaces that seem to function as lateral lines do in Earth fish.

Amphibians
Amphibious lifeforms exist that bare some resemblance to salamanders, lizards, and snakes, but not to anurans (frogs and toads). Some can be fairly large; about the size of an alligator.

Reptiles
Reptile-like animals are abundant on Atar, including forms which have no Eartian analogues, such as the serpines. One group, the Aviosauria, fly using feathers, some with all four limbs as wings. They somewhat resemble feathered lizards or early birds, and occupy similar ecological niches, but morphologically true analogues to modern birds do not exist on Atar.

Mammals
Mammal-like Atarian animals exist that exhibit some mammalian traits such as endothermy, fur- or scale-like keratinous integument coverings, a primitive form of lactation, and four-chambered hearts pumping hemoglobin-rich blood through a closed circulatory system. Kidneys are fused in the scypheramorphs. Some are viviparous, with a large group of those even baring an organ that is visually and functionally identical to the placenta.

Atarian analogues exist for carnivorans, rodents, moles, lagomorphs, pinnipeds, and ungulates. Arboreal forms exist, such as some jungle scyphers, but none are substantially primate-like. Although many different groups, including Atarian mammals, evolved aquatic and marine lifestyles, none are known to have survived to present that have attained the sizes of cetaceans.

Plants

 * Spriggs
 * Protoids
 * amienes

Animals

 * Scyphers: euscyphids, urscyphers, myumauds
 * Darrels
 * Purons
 * Serpines
 * Aviosaurs
 * Brinches
 * Gwarfish