Hornsnail
Basic Information
Anatomy
The hornsnails are small, soft bodied herbivorous organisms with stocky, pudgy bodies and small heads. Segmentation on their bodies is still present - a leftover trait from their Xenoeuly ancestry - and nonfunctional opsin clusters remain present. The number of segments has been significantly reduced, however, as segments three, four, and five have completely merged into one segment with the first four limbs. Segments six and seven have also merged, and now consist of the back two limb pairs. Segments eight, nine, and ten are merged in the original cephaloptin ancestor, however in the hornsnails this tagma has shrunk significantly, and now serves simply as the container of the posterior anus and gametes.
The organisms possess four bony fins, each located on the underside of the body. These fins serve as walking limbs, and have the ability to grasp the sediment due to their internal anatomy. Within each fin rests a set of several bones, each with several muscles between them. The bony structure itself is anchored to the notochord through a long muscular hydrostatic structure. These anatomical features exist in at least some form within all cephaloptins, and within the hornsnails they are used to create a walking structure. These limbs serve to help anchor the hornsnail to the sediment, and when combined with muscular hydrostatic structures lining the interior of the body and connecting them to the notochord, allow the organism to walk along the substrate.
These limbs serve the additional purpose of allowing the hornsnail to dig into the sediment if danger approaches. Due to its general lack of bones and soft body, the hornsnail possesses the ability to squeeze itself into openings far smaller than itself; given the organisms already small initial size, the hornsnail is capable of squeezing into spaces as small as 10 millimeters.
Within the horn snail's body tagma exists an esophagus, on the roof of which exists a small pouchlike ridge that contains two ctenidia. These ctenidia serve as the primary respiratory organs for the creature, as it’s gill fronds - while still functional - are located in a highly unfavorable position for acquiring oxygen from the surrounding water. Thus, these gills are used principally as a means of removing carbon-dioxide and other aqueous waste products from the bloodstream, while the ctenidia are used for both acquiring oxygen and expelling carbon-dioxide.
The esophagus connects to a hatch-protected stomach, which can open to allow food and particulates to enter the organism’s system. This stomach is connected to a gland system, which produces stomach acids and enzymes to digest food. This in turn connects to a long, winding intestinal tract that runs from the stomach to the posterior anus. As this organism does not contain a bladder to hold waste products, they are expelled the moment the posterior anus is opened (it may be sealed with a small muscular hydrostat surrounding the rear of the intestinal tract shortly before the opening).
Within the mouth of the organism rests a radula covered in small keratin teeth anchored to an odontophore located on the roof of the mouth. This radula can be pushed downwards to effectively seal the mouth, and is used to ensure that edible material is ground into fine particulate as it is scraped off of the sediment and sent through the mouth and into the esophagus. Behind this is a pair of osphradia, which are used to gain information regarding the type of particulate entering the organism’s throat. This allows it to roughly gauge if the particulate it is consuming could be harmful to it’s ctenidia, and thus helps it ensure that the water it is intaking does not possess harmful particulate. These organs function can double as a means of ensuring that food particulate is ground up enough for efficient digestion, however this process (governed by instinctive behaviors) are incredibly basic and are insufficient to properly measure how well “chewed” it’s food is.
The nervous system of this organism is, like most other thalassalinkarians, quite basic; it consists of a simple cluster of nerves in the upper portions of the head tagma, two bilateral nerves running alongside the notochord, and two neural rings connecting them within the body tagma. Connected to this are three pairs of statocysts filled with a small amount of haemocyanin and air. These statocysts are utilized by the organism as a means of detecting gravity, and are located at three strategic portions of the organisms; one pair is in the cranial tagma, and one is between each pair of limbs. This allows the organism to detect how gravity is acting on its body, and thus allows it to position itself in favorable positions for feeding and retreating from predators.
Perhaps the most surprising anatomical feature of the hornsnails is their cranial tagma. Like all cephaloptins currently in existence, the hornsnails possess four distinct camera-type eyes. However, in the hornsnails, these eyes are located on long, muscular hydrostatic structures resembling the arms of cephalopods or the antenna of snails and slugs. Each eye is located on a separate tentacle that possesses a significant range of motion. This is the hornsnails main method of defence - detection. By placing eyes on a long hydrostatic structure, the organism is able to maintain an extreme range of vision at all times and can effectively watch for danger both while feeding and hiding. Through its use of the camera-type eye, the hornsnail can detect danger from a significant distance. Though it lacks stereopsis, the simple ability to see danger is enough for the creature to begin burrowing into the sediment. As a hole does not need to be particularly large, the organism is capable of burrowing rather quickly or escaping into crevices that are impossible for predators to reach. It can then use it’s four eyes to peer out from its hiding location to see if it is safe to emerge.
As an interesting side note, hornsnails get their name from these muscular hydrostatic structures holding the eyes. These structures were originally misidentified as horns in the holotype due to their position and appearance, thus the name hornsnails. However, it was later determined through analysis that these organs were in fact muscular hydrostatic structures, not horns.
Genetics and Reproduction
Hornsnails are diploid hermaphroditic organisms. In the third tagma, on either side of the notochord is a gonad. One gonad is male, and the other is female. When conditions are optimal - usually defined by the warm, nutrient rich waters of the summer months - and assuming the hornsnail is healthy, hornsnails begin to release hormones and enzymes bound to waste material into the water. These hormones are detected by the osphradia, which allows the hornsnail to follow the “scent”.
When the hornsnail has located a mate, they will begin to dig a burrow or locate a suitable mating site nearby. Possible sites include crevices between reef structures and under rocks. When a proper nesting site is found or completed, the hornsnails will each lay their eggs before fertilizing the other’s. The hornsnails will guard the fertilized eggs for one week until they hatch, after which the hornsnails will leave the area and feed for several days to regain strength. Afterwards, assuming conditions are still optimal, the organism will attempt to mate again.
Growth Rate & Stages
The initial stage of life begins with eggs, which are laid in clusters of 20-50 in a suitable burrow. During gestation, the parental hornsnails will attempt to protect and incubate the eggs to ensure that optimal environmental conditions are maintained for development. However, they will prioritize their own lives over their eggs, and will still flee from predators if given the chance to do so.
After 7 local days, the naiads will emerge as miniature versions of the adults. These small organisms are barely large enough to prevent themselves from being dragged off by the current, and must cling to the substrate until they are large enough for their weight to anchor them down. During this time, they will feed exclusively on small algae-like retinalphytes and phytozoans growing on rocks and corals. Some may even live among the structures of fortressmisas, eating small plants growing along the structures.
After about 7 local days, the young hornsnails are large enough for their weight to anchor them to the surfaces they crawl on. It is also around this time that the young hornsnails will begin to feed on small animals and occasionally scavenge carrion; for those that live near fortressmisa hives, a ready source of food in the form of scraps from scavenged materials and leftover biomass on the shells. For others, algae-like phytozoans and retinalphytes with supplementary carrion and microbes is sufficient.
After an additional 14 local days, the hornsnails reach their adult size. By this point, the gametes develop fully and sex hormones begin to be produced. These hormones will be released when conditions become favorable for reproduction, and at this point the organism is considered to have reached full maturity.
Ecology and Habitats
The hornsnails prefer habitats where there are plenty of structures for them to burrow into or crevices to use as hiding places. For this reason, they prefer the crowded, shallow seas of the Yama-Kub Shay reef system where crevices and food are abundant. As they lack any form of hardened carapace (or external defensive structures in general) their main strategy to escape predation is to flee as opposed to fighting. hornsnails tend to avoid confrontations when able, and exploit their flexible, muscular bodies in doing so.
When confronted with a predator, hornsnails will quickly use their eyes to observe their surroundings. If able, they will flee into tiny crevices between reef builders and rocks, and if unable they will begin to burrow deep into the substrate. Their fins are bony, and the muscles controlling them are some of the strongest in the creature's body. As a result, the organism is able to burrow deep into the substrate fairly quickly. The organism will prefer to hide in these crevices until the danger has passed, after which it will leave and resume it’s normal behavior.
Thalassierpeto salinkari - The Quadrahorn Snail
This species lives around the southern tip of Yama, as well as all across the shallows of north west and western Kub Shay.
Thalassierpeto hydra - The Yamahorn Snail
This species lives around Yama on all but the northern coast.
Keratomati tenome - The Artahorn Snail
This species lives around the east and southeast coast of Arctica, the east and northeast of Yama, and the northern most parts of Kub Shay.
Keratomati mikroa - The Flathorn Snail
These live all through the Yama-Kub Shay major reef system as well as smaller population around the north east coast of Yama.
As a hornsnail has practically no defenses if caught, all of its biological adaptations regarding escaping predation are dedicated to escaping via. retreating to locations where predators cannot follow. This has proved quite effective against most predators, however it has also led to some predators specializing to hunt them specifically, as they are a fairly nutritious and reliable food source for such a predator.
Dietary Needs and Habits
The specific dietary needs vary between species, however the general diet remains the same. hornsnails are primarily herbivorous organisms, feeding on small sprouts and algae-like retinalphytes and phytozoans. Between the two, hornsnails are significantly better at digesting phytozoans due to the composition of enzymes produced by their digestive gland; the exception to this is Keratomati mikroa, which prefers to digest retinalphytes. This switch is in part due to the presence of chemochoids within its digestive tract, as several byproducts of their reactions are useful in synthesis of digestive enzymes or play a direct role in digestion.
Rather than rely entirely on herbivory, hornsnails also act as opportunistic scavengers when the opportunity arises. In addition to this, they will also digest xenometazoan microbes as well, though this plays a far less significant role in their diet. The reason they do this is to gain easier access to proteins and amino acids that are easier to digest than those in retinalphytes and phytozoans. Their diet is still primarily herbivorous in nature, thus allowing them to avoid competition with other scavenging organisms within the reef system.
As another means of supplementing their diet and gathering means of aiding in digestion, hornsnails will also consume debris and small pebbles in the substrate. These gastroliths serve two main purposes: digestion and symbiosis. Hornsnails utilise gastroliths as a means of aiding in breaking up small clumps of plant matter, grinding them into even finer powder to further aid in digestion. Additionally, these gastroliths aid in the cultivation of pockets of chemochoids that produce compounds useful in digestion, enzyme production, and pH regulation. This chemochoid cultivation is not necessarily deliberate (the Flathorn is an exception) but rather simply a beneficial side-effect of the consumption of gastroliths and life on the seafloor.
Keratomati mikroa
Unlike most hornsnails, the flathorn prefers to consume and digest retinalphytes as opposed to phytozoans, and have adapted their digestive enzymes to do so. In addition to producing enzymes to attack the cell walls of retinalphyte autotrophs, the flatworms make use of a greater variety of digestive acids that are produced by chemochoid symbiotes living within their gut, which feast on the carbon-dioxide produced by cellular respiration.
The flatworms possess many blood vessels that diffuse carbon-dioxide into the digestive gland, where most chemochoids reside within the creature. They then use enzymes and transporting hormones to secrete productive byproducts into the stomach and bloodstream, while harmful byproducts are sent directly to the posterior anus.
Due to an increase in the need of mineral compounds, the flatworm will consume a larger quantity of gastroliths to help grind up plant material. Most hornsnails make use of some gastroliths to help further grind plant material; however, the flathorn regularly consumes debris to supply it’s chemochoid symbiotes with minerals to perform chemosynthesis and produce helpful byproducts that can be utilized by the organism.
Additional Information
Facial characteristics
Thalassierpeto salinkari - The Quadrahorn Snail
The Quadrahorn snail is a species of hornsnail descending from the western shores of Kub Shay, and spends most of its life in the shallowest regions of the reef system that are sufficiently distant from the murky river outlets. These organisms possess four long eyestalks that are relatively identical to each other. This type of Hornsnail is one of the most common on Almaishah, and has a range extending from southwestern Yama to Northern Kub-Shay.
Thalassierpeto salinkari - The Yamahorn Snail
The Yamahorn snail is closely related to the quadrahorn snail, and shares a portion of it’s range with it. However, unlike the quadrahorn snail, the yamahorn snail’s range consists of the coastline of Yama - hence the name yamahorn. As the continent of Yama consists of more lowlands, estuaries, and wetlands, the Yamahorn has adapted to cope with waters that may be merkier. It’s eyestalks have grown significantly longer than those of the quadrahorn to grant it greater visibility away from its body, and it’s osphradias have adapted to becoming somewhat of scent-detecting organs. In this way, the yamahorn is able to smell organisms in a way that is somewhat analogous to “tasting” the water for them - thus helping it detect predators in the event its eyes become ineffective.
Keratomati tenome - The Artahorn Snail
The artahorn snail gets its name from its range, much like the yamahorn - rather than inhabiting the shoreline of Yama, the artahorn lives around the southern coasts of Artica (with some small populations living in northern Yama and Kub-Shay, where competition with other Hornsnails is reduced). These hornsnails, while visually more similar to the genus Thalassierpeto, are actually more closely related to the flathorn - in fact, fossil analysis indicates that these two organisms were so closely related that they were likely part of the same genus - Keratomati. The artahorn snail lives a similar lifestyle to other hornsnails, however it is better adapted to more extreme seasonal weather fluctuations in temperature and the day-night cycle. As such, it has succeeded in out-competing encroaching populations of the genus Thalassierpeto.
Keratomati mikroa - The Flathorn Snail
The flathorn snail is by far the most unusual, at least compared to other members of it’s family. Unlike most hornsnails, its eyestalks are actually quite short and stubby. It is likely that this organism is closer to the ancestral hornsnail, as there is no fossil evidence of a regression of eyestalk length from this period. While the flathorn snail lacks the large range of visibility that other hornsnails possess, it does possess a more specialized digestive system more specifically tailored to retinalphytes, thus avoiding competition. It’s flat eyes, while unable to rotate for 360 degree vision, do provide the organism with exceptional front-oriented vision. Thus, while this species must turn its head in order to observe its surroundings, it is able to better analyze visual information; resultantly, this species also demonstrates superior decision-making skills as opposed to its relatives.
Perception and Sensory Capabilities
The hornsnail, like all other cephaloptins, possesses a camera-type eye. This visual sense serves as the primary mechanism for protection against predators and environmental hazards, as it allows the organism to detect danger visually from great distances - often times around 100 meters or more in ideal conditions. Additionally, neurons lining the underside and limbs of the organism allow it to readily detect sediment conditions beneath it. These two senses allow the organism to maintain awareness of its surroundings constantly, thus helping it detect dangerous conditions before they can impact the creature’s life.
In addition to these sensory organs, the hornsnail possesses six statocysts arranged in three pairs throughout its body. Each statocyst contains gasses such as carbon-dioxide expelled from the bloodstream and a small amount of haemocyanin or water. Within this organ are thousands of tiny cilia, which are used to detect the orientation of the liquid in reference to the gasses contained inside. These organs allow the hornsnail to know how it’s body is oriented relative to the direction of gravity (down), and thus aid it in positioning it’s body and maintain awareness of the organism’s location in the environment.
Lastly, the hornsnail possesses an osphradia just behind it’s radula. The osphradia is designed to function as a means of detecting particulate matter within the water column. This organ allows the hornsnail to maintain a relative awareness of the water it is intaking into its stomach and exposing its ctenidia to, thus helping it ensure that it does not intake harmful sizes of particulate. This organ also serves other purposes for the hornsnail; notably, it can help the organism ensure that it’s food is ground efficiently so that it may be easily digested, and can also help the organism maintain awareness of the consistency of the water in ways other than sight. If the water is particularly murky, the organism can detect this both through visual indicators and through employing it’s osphradia. Based on this information, the hornsnail is able to act accordingly to protect its gills while still maintaining necessary gas exchange for its metabolism.
EXTINCT
Genetic Ancestor(s)
Scientific Name
Thalassierpeto sps. & Keratomati sps.
Origin/Ancestry
Xenosegmenta
Lifespan
Thalassierpeto hydra: 5 local years Thalassierpeto salinkari: 7 local years Keratomati mikroa: 5 local years Keratomati tenome: 4 local years
Average Height
Thalassierpeto hydra: 4 cm
Thalassierpeto salinkari: 5.5 cm
Keratomati mikroa: 4.8 cm
Keratomati tenome: 3.9 cm
Average Length
Thalassierpeto hydra: 8 cm
Thalassierpeto salinkari: 12 cm
Keratomati mikroa: 10 cm
Keratomati tenome: 8 cm
Geographic Distribution
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