Pudgeworm

Crawling amongst the sediment of ancient Almaishah is a small, wormlike creature with legs. It’s body is small and simple, as is it’s lifestyle. As it slowly filters the sediment along the seafloor, it wiggles it’s body in a caterpillar-like motion - gripping the rocks and sand with it’s tiny, bony fins. The creature itself is fairly strange - while it clearly shows vestigial signs of segmentation and repeating opsin clusters like a xenosegmatan, it also has a body plan resembling that of a paleotagmatan. With it’s four camera-type eyes, it looks around the water column, observing it’s surroundings and watching for predators - burrowing itself deep into the ground at the sight of danger. While it may not seem like a particularly important organism to an observer, its discovery was actually one of the most significant in terms of the study of ancient Almaishah. In fact, this tiny organism is the basal member of a clade of organisms known as cephaloptinae. Thus, this discovery was one of the most important for the study of the clade - as well as the study of evolution as a whole. As the pudgeworm is one of the closest animals to the common ancestor of a clade on almaishah discovered thus far, the study of its anatomy has led to important breakthroughs and insights on the evolution of the strange xenosegmatans that make up the clade cephaloptinae. Pictured here a pudgeworm inches its way across some sand looking for a new hiding place. [Creature design by Lethal Cuteness]

Basic Information

Anatomy

This anatomical diagram shows some of the important organs of the pudgeworm, which are referenced and explained in greater detail below: Bright Red: Cranial Neuron Cluster Yellow: Esophagus Azure Blue: Ctenidia - Internal gill structures shaped like feathers Purple: Odontophore - Bony plate that anchors radula, located dorsally Dark Orange: Radula - Rasping tongue-like structure lined with small keratin teeth Aqua: Eyes Dark Yellow: Statocysts - Small pouches with fluid, measures direction of gravity Light Brown/Sand: Stomach Rust Orange: Digestive Gland Pink: Tubular Intestine Light Orange: Stem - Notochord-like structure Dark Brown: Gonads Grey: Cartilaginous bones - *Not shown on Cranial tagma due to size Clear: Haemocoel - Central cavity of the circulatory system Green: Locomotive Muscles The pudgeworms anatomy is fairly basal, yet it differs considerably from most other xenosegmatans - indicating that the divergence of cephaloptins from other xenosegmatans is quite ancient. It’s external anatomy can be divided into three distinct tagma:
Cranial - the cranial tagma contains organs regarding sensory information, most notably the eyes. It is also responsible for the intake of materials from the environment into the body. Abdominal - the abdominal tagma contains most internal organs essential to life, such as the central circulatory system, digestive tract, and most muscle groups responsible for locomotion. Posterior - the posterior tagma contains the posterior anus and gonads, and is responsible for materials exiting the body and being released into the environment.
The cranial tagma consists of the merged segments 1 and 2 present on Xeneuli kirbiyi. Externally, the finlike appendages remain present, however are mostly vestigial. Despite this, they still contain the same number of cartilaginous structures present in every other fin (with the exception of the primitive tail fluke). Seven cartilaginous “bones'' are located within these four fins, and lack any connections to the rest of the body via. muscle whatsoever. They are maintained by a simple supply of blood, but there is little other connection with the rest of the organism’s body. The four eyes of the pudgeworm are descended from opsin clusters located on the first two segments of more basal Xeneuli descendents (as well as Xeneuli itself). Each of these eyes is a camera-type lens eye, capable of moderate resolution up to 40 meters away. These eyes consist of a U shaped pupil, cornea, retina, lens, ciliary body, iris, and vitreous body. The eyes grow from the skin and body-tissue of the pudgeworm during its larval phase, and most closely resemble the eyes of cephalopods on Earth. Likewise, the optical nerve protrudes out of the eye from behind without overlapping any optically sensitive cells, resulting in the lack of a blind spot. The optical nerve leads into a large cluster of neurons located within the dorsal side of the cranial tagma, just above the odontophore. This cluster of neurons is not a brain, however it does resemble the early development of one. The cluster of neurons is mainly dedicated to the processing of sensory information from the eyes and statocysts, and disseminates this information to the rest of the nervous system through two long neural cords running on each side of the stem. Below the proto-brain rests the oral cavity. Surrounding the exterior side is a set of muscular hydrostatic structures operating as a sort of “lip muscle” that enables the pudgeworm to seal and open the oral cavity as necessary. Inside of the oral cavity rests a radula - a tonguelike structure lined in numerous small keratin teeth specialized for rasping and scraping material off of surfaces. This radula is anchored to a cartilaginous odontophore situated on the roof of the mouth, which enables the radula to move downwards into the oral cavity to scrape up material and grind it within the oral cavity before sending it to the esophagus. This radula likely evolved from filter feeding structures located within Kirbiyi’s oral cavity, as a benthic lifestyle necessitated structural modifications to allow filter-feeding of plant material from larger rocks and sediment. Within the cranial tagma exists two statocysts. These organs are small pouches located within the interior of the organism that are lined with cilia hairs. These cilia hares are in turn connected to highly sensitive nerve endings that detect changes in the movement of these hairs. Within the statocyst is a small amount of fluid - usually hemocyanin diffused into the organ by local extensions of the haemocoel - which always flows to the bottom of the statocyst. As it does so, it triggers vibrations within the small hairs, thus allowing the pudgeworm to know how it is oriented in relation to gravity, and thus always know what direction it is burrowing.
The abdominal tagma consists of the space of the organism located between the cranial and posterior tagma, and is responsible for the housing of most organs - the largest system of which is the digestive tract. The esophagus, while connected to the cranial tagma, is mostly located within the abdominal tagma and is usually considered as part of this tagma when discussing cephaloptin anatomy (with some exceptions). The esophagus contains numerous organs - first of which are two osphoradia. Each osphoradia is located on an opposite end of the oral cavity - one on the anterior and one on the dorsal side. These osphoradia are used to detect particles within the esophagus. This role is interestingly vital to the pudgeworm for two reasons. The first of these is that the osphoradia enables the pudgeworm to know how well chewed it’s food is, so as to know how much more it needs to chew incoming particulate. The second purpose is it allows it to know if any harmful particulate is entering the esophagus via. the water column. This second function is crucial, as the esophagus also houses another important structure for the pudgeworm - the ctenidia. Within the dorsal side of the esophagus exists a large groove, creating a degree of open space at the top of the esophagus. Within this space is a pair of ctenidia - one located on each side of the groove. The ctenidia function as internal gill structures, and are a unique adaptation to the cephaloptins. It has been proposed that these structures evolved from a combination of the framework of filter-feeding structures and blood vessels, but no theories have been proven definitively at this time as not enough is known about Kirbiyi’s internal anatomy to reach a satisfactory conclusion. What is certain is that the ctenidia evolved as a response to the external gill fronds being pressed against the seafloor continuously - thus restricting access to oxygen. Thus the ctenidia and the anterior gill-fronds partition the goals of a respiratory system. The ctenidia’s primary function is to bring oxygen into the bloodstream, while the anterior gill fronds main function is to remove CO2 and soluble waste products as efficiently as possible. At the base of the esophagus rests a small valved chamber which opens into a single chambered stomach. This stomach is the largest organ within the abdominal tagma, and its purpose is to digest both food and waste products into a soluble form. To accomplish this task, the pudgeworm has evolved a large gland attached to the stomach to produce enzymes and acids required for digestion. This organ is referred to as the digestive gland, as it evolved from a swollen hormonal gland in segment 4 of Xeneuli kirbiyi and its purpose is related to digestion. The back of the stomach is a small groove structure which contains a valved opening. This valved opening opens into a long, tubular intestinal tract which runs across the remainder of the abdominal and posterior tagma. Within the intestinal tract are numerous symbiotic microbial organisms (such as chemochoids) which aid in the breakdown of dissolved food and particulate to a form that is soluble within the bloodstream. Long passages of porous, folded membranes within the intestinal tract ensure efficient diffusion of resources into the bloodstream so that they may be utilized or disposed of via. respiration. Just behind the stomach rests a large cavity within the body. This cavity, referred to as the haemocoel, is the central portion of the pudgeworm's circulatory system. The haemocoel is connected to numerous passages that extend throughout the body, all of which are lined with muscular hydrostatic structures dedicated to pushing blood through the passages. While this type of circulatory system is not closed and no form of heart is present, it is sufficient to ensure efficient nutrient distribution across the pudgeworm’s body and intricate muscle structures. Running along the middle of the abdominal tagma and oriented slightly dorsally, a long tubular structure composed of cartilaginous material serves as the anchor point for most of the central musculature. This organ is referred to as the stem, and strongly resembles the notochord of the chordates of Earth. However, unlike notochords, the stem does not serve as a protective organ for the nervous system in any way (although two neural cords do run parallel to it on either side). Rather, this chord evolved as an anchor for the numerous muscular hydrostatic structures involved in the creature's locomotion as it crawls across the seafloor and extends/bends its body. Running parallel to the stem on each flanking side, two long neural cords run from the proto-brain in the cranial tagma to the end of the stem at the base of the abdominal tagma. These nerve chords serve as the central routeways for information to be sent across the body. Information from statocysts attached to the cords between each pair of limbs route their information through these cords, as does information collected by the proto-brain. This information is then utilized as a means of reacting to stimuli at a fairly instinctive level. The purpose that the long cords serve is a quick and efficient routeway for reactions to be sent across the organism’s body. While these reactions are still heavily instinctive and the pudgeworm lacks learning capabilities to any extent beyond the most basic levels, the efficiency of the nerve cords allows complex responses to stimuli to be carried out based on instinctive reactions across the body. The abdominal tagma also contains a vast degree of musculature. The pudgeworm’s musculature is based almost entirely on muscular hydrostatic structures running all throughout the body. These structures, while primitive, are quite strong and capable of exerting extreme strength by utilizing the stem and bones located within the fins as a means of support. Thus, their innate strength is able to be amplified significantly into powerful gripping, pushing, and pulling muscles that govern the creature’s locomotion.
Within the posterior tagma exists two organs of note, as this tagma is dedicated to the expulsion of waste and gametes. The intestinal tract connects to the two gonads through small tubular structures that converge at the posterior anus. This posterior anus is almost completely unchanged from that of Xeneuli kirbiyi, except that it is surrounded by a muscular hydrostatic structure in a similar way to the mouth. The gonads themselves are of different sexes, rendering the pudgeworm a simultaneous hermaphrodite - it possesses one male and one female gonad.

Genetics and Reproduction

The pudgeworm is a diploid hermaphroditic organism - it possesses one male and one female gonad that are functional and produce gametes simultaneously. These organisms lack any form of mating season - their range is exclusively equatorial. When these organisms accumulate a critical amount of gametes, they will expel them similarly to waste products through the posterior anus. In the case of female gametes, they are laid as clusters of eggs ranging from clutches of 10 - 20. Male gametes are released as small plumes. When a pudgeworm comes across a clutch of eggs, it will place it’s posterior anus over them and release all of its accumulated male gametes - fertilizing the eggs. The pudgeworm will interestingly do this if it discovers a clutch of eggs it lays itself, and it is not uncommon for a pudgeworm to lay its own eggs, tunnel away, rediscover its clutch of eggs and fertilize them itself. This is not intentional - the pudgeworm itself has no way of remembering what clutch of eggs are its own. Thus, because their processes are instinctive, they will attempt to fertilize any clutch of eggs they find that belong to their own species.

Growth Rate & Stages

Pudgeworm eggs hatch after about 1-2 local days, from which small naiads will emerge. These naiads are identical to adults in every way except for their small size and lack of developed gametes. The naiads are oftentimes around 1-2 millimeters in length - however, their strong fins are able to hold them to the sediment - should they let go, they will certainly die. The pudgeworm naiads will feed on small flakes of detritus and microbes as they rapidly grow - the entire growth of a pudgeworm from 2 millimeters to 1-2 centimeters takes only 5 local days. However, the gonads do not reach maturity until 10 local days - after which gametes of both sexes begin to be produced in large numbers, thus signifying the beginning of adult life. Pudgeworms have very short life expectancies - most do not live past 60 local days. However, during this time they will often fertilize hundreds of eggs - thus contributing to the overall success and rapid evolution of the species. This is likely the main reason why pudgeworms have evolved so rapidly in Almaishah’s oceans: in the amount of time it takes one species to cycle through a generation, pudgeworms have gone through 4-10. Thus, while they live short lives, the species is able to breed rapidly and thus produce a favorable climate for rapid evolution.

Ecology and Habitats

Pudgeworms live around the equatorial waters of eastern Kub Shay, and also around nearby islands.

Dietary Needs and Habits

Pudgeworms are benthic generalists, and will consume a wide variety of food. Small pockets of chemochoids are consumed to provide symbionts for the intestinal tract, while retinalphytes and phytozoans are gnawed at for a source of complex carbohydrates via. flakes of their stems and leaves that can be scraped off. Proteins are usually acquired through filter feeding sediment for microbial organisms and algal-like producers, which are digested as a primary energy and protein source. Additionally, small grains of sediment are ingested to serve as gastroliths which aid in the digestion of flakes of plant material. Detritus will also be readily consumed, as it is one of the best sources of proteins and lipids for a pudgeworm. Perhaps the most common prey item for pudgeworms are mycoids, which are consumed in bulk by pudgeworms as a ready source of carbohydrates and proteins. In fact, it may be true that pudgeworms initially evolved to filter mycoids from the sediment. Due to their abundance around carrion, pudgeworms can be found swarming these locations - consuming mycoids and scavenging small flakes of meat from the carrion.

Additional Information

Perception and Sensory Capabilities

The pudgeworm has numerous sensory organs - the three most notable are osphradia, camera-type eyes, and statocysts. The osphradia - located within the esophagus - are specialized organs capable of detecting particles within the water column. These organs effectively serve as primitive feeling organs, taste buds, and scent-receptors in the form of one organ. While none of these features are well developed (with exception of their ability to feel for particulate’s existence), their presence indicates the potential for a great deal of sensory detection, if only on a basic level. The camera-type eyes possess enough resolution to create accurate images from up to 40 meters away. While this resolution is not the most advanced present on Almaishah, the resolution is significant for a small benthic burrowing organism. Thus, the pudgeworm is able to see predators from a very long distance away and react accordingly - indicating why superior vision was selected for amongst their X. kirbiyi ancestors. Furthermore, the pudgeworm is one of the few primitive organisms to have developed a camera-type eye so early, thus granting it and its descendants a key advantage over other organisms in their ecosystems. The statocysts, while some of the smallest sensory organs within their bodies, are among the most important anatomical features of the pudgeworm. As sight and touch are unreliable for determining direction when underground, an organ to allow an organism to detect what direction it was moving underground was selected for among pudgeworms and their X. kirbiyi ancestors. Thus, several small pockets within the haemocoel of Xeneuli kirbiyi on segments 2, 4, and 7 were separated from the rest of the circulatory system and adapted to be utilized as a type of sensory organ. Cilia hairs were developed lining the interior, and neurons were attached to the structure. The result was an organ that could be utilized as a means of detecting the direction of gravity, which would allow the pudgeworm to differentiate between up and down while underground. Other than these organs, pudgeworms possess a nervous system that is capable of transmitting sensory information from the skin, fins, and some internal anatomical features through the nervous system. These kinds of sensory information can include temperature and a sense of damage, as well as a basic sense of texture (for instance, if a surface is slippery, smooth, or rigid) but little else. This nervous system is basic, however does allow the pudgeworm to gain an understanding of the sediment around it as it digs and searches for food.

Symbiotic and Parasitic organisms

Pudgeworms oftentimes form symbiotic relationships with benthic layer microbial organisms that they accidentally ingest. Most famous of these are the chemochoids, which rapidly colonize the guts of the pudgeworms and feed off of the large amounts of sediment that find their way into the digestive tract by accident. These sediments are broken down into a form that can be expelled - and in some cases incorporated into vital compounds within the pudgeworm such as amino acids, proteins, lipids, enzymes, and other important biological molecules.

Genetic Ancestor(s)

• Xenoeuly kirbyi

Scientific Name

Thalassi exypnada

Origin/Ancestry

Xenosegmenta

Lifespan

60 local days

Average Height

0.2 cm

Average Length

1 cm