Dissection Notes of Subject #182(1)
Date: April 16th, 2022
Days since Collision: 837
Log by Dr. Franklin Cliffestone
Subject #: 182(1)
Content: Dissection
Species: Mermaid
Little has been documented of the elusive mermaid species since the 2020 Collision on Earth Beta. Most mermaids live at depths below what funding would allow. I have been afforded the opportunity to preform the first recorded dissection of this species. The subject is female, though all recorded observations of mermaids to date have been female. It is unclear how this species reproduces at this point. Hopefully, this dissection will shed light on this conundrum.
The subject was captured at a depth of 400 meters off the coast of [REDACTED] in Earth Beta. The team responsible captured the subject in relatively good condition. The subject expired due to suffocation outside of water shortly after capture. It was held on ice for 52 hours before arrival in this research facility on Earth Prime, it is unlikely to have sustained any damage during travel.
External Anatomy
Subject has the upper body of a human woman; the torso extends to two (2) inches below the navel upon which the epidermal tissue gains an ichthyosis like condition. This however is a human approach to the subject’s anatomy, the tissue on the tail is closer to genuine fish scales than any ichthyosis recorded in modern medical history. The subject has notably more adipose tissue in the subcutaneous level than a human equivalent. I postulate that this extra adipose tissue is to conserve heat in the underwater depths of Earth Beta.
The subject lacks most of the fins one would expect to find in an aquatic species. The subject has no dorsal fin, pectoral fin, pelvic fin, or anal fin. The only fin the subject has is a large caudal fin. Due to the absence of stabilizing fins and side-to-side motion fins, I theorize that the subject uses its caudal fin for explosive and long-distance movement while it uses its arms and hands for stabilization and micro-movement underwater.
Concerning the dermal tissue of the human torso, the subject has several signs of hypohidrotic ectodermal dysplasia (HED). The subject has a complete absence of sudoriferous glands (sweat glands) and bodily hair follicles. These have potentially become obsolete in the evolutionary pathway due to the nature of the living conditions. The subject does not display any other facial abnormalities associated with HED such as malformation of teeth, prominent forehead, sunken nasal bridge, unusually thick lips, or a large chin. The subject still retains hair on the scalp, due to strength and colour it does not appear the subject was malnourished.
Comparing the features of the superior half of the subject to a human female, few differences are noted. Aside from the previously mentioned absence of sudoriferous glands and bodily hair follicles, the subject several differences in external anatomy. The subject has syndactyly between each phalange on both hands. I presume this is for extra mobility in water. The subject also has oblique gill slits running across its neck.
The subject’s skin is an albino white. Examination of the epidermis shows an almost complete absence of melanocytes. This is likely due to the depths at which the subject lives being without UV rays, thus eliminating the need for pigmentation. It is possible that this subject is unique in its condition, though the probability of this is very unlikely, as albinism would present with red irises which are absent in the subject.
Internal Torso Anatomy
Beginning the dissection with a cephalostomy, several things were uncovered. The teeth of the subject resemble that of a carnivorous animal leading to my assumption that the diet of the subject consists solely of meat. More will be uncovered once I reach the subject’s stomach. The brain of the subject appears identical to that of a human. If the subject was still alive, we could preform a fMRI scan to learn more about the brain activity. The brain of the subject weighs approximately three (3) pounds. The cervical vertebrae of the subject appear identical to that of a human, including the nerve roots of the brachial plexus. A notable departure from human anatomy is the subject’s absence of sinuses. In their place, the subject has a melon structure reminiscent of that found in dolphins. This likely allows the mermaid to preform some level of echolocation.
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Unlike in humans, the subject has two completely separate tubes in its neck. One of these tubes is the esophagus, which directly links the mouth to the stomach. The other tube acts as the trachea. It is not, however, connected to the mouth the way it is in humans. Instead, the ‘trachea’ acts as a funnel that all the gills in the neck lead to. The gills which were previously mentioned on the neck of the subject are different than the gills which would be found in fish on Earth Prime. In regular fish, the gaseous exchange occurs directly inside the gills, with the oxygen diffusing across the capillaries. In the subject however, the gills collect water from the outside environment and transport it into the lungs in a similar way that we do with air.
Examining the thorax, we explore more about the respiratory system of the subject. The subject still has the same muscles for inhalation and exhalation which are found in humans, if not with different origins and insertions. The primary theory for the transport of water appears the same as that for air. The ventilation muscles work to expand the thorax which decreases pressure causing water to enter the lungs, then the ventilation muscles work to contract the thorax which increases pressure causing water to exit the lungs. This however brings the question of ventilation during high speed travel underwater. Assuming the subject can travel at high speeds underwater, exhalation would become unnecessarily difficult for the subject as forcing the water out of the lungs against the current is excessive. I suspect that the subject compensates with a cleverly designed system of tubes and pathways which allow for the flow of water through the lungs to continuously move forward to expel from the lungs with minimal effort. It is possible with this method that exhalation for the subject is a passive process, like it is in humans, while in motion.
The heart in the subject appears the same as that of a human. It is a 4 (four) chambered organ with the same location and number of pulmonary veins and arteries. The subject’s heart also has a superior and inferior vena cava as well as an aortic trunk. The aorta splits into 3 (three) branches - the brachiocephalic artery, the left common carotid artery, and the left subclavian artery. The descending aorta still descends posterior to the heart. The heart of the subject has the same electrical system as ours, with both a sinoatrial node and an atrioventricular node.
The subject has a diaphragm separating the abdomen from the thorax. It is identical to the human diaphragm, the inferior vena cava passes through the caval opening in the diaphragm at the 8th thoracic vertebrae, the esophagus passes through esophageal hiatus in the diaphragm at the 10th thoracic vertebrae, and the aorta passes through the aortic hiatus in the diaphragm at the 12th thoracic vertebrae.
The subject’s stomach is of similar structure to that of a human. Examining the contents of the stomach reveals several different species of fish, two of which are unknown. Examination of the stomach acid reveals a lack of any enzyme capable of breaking down starch or other plant-based molecules, this confirms my suspicion of the subject being carnivorous. In the subject’s abdomen, we find the same organs we would expect to find in a human, with the addition of a swim bladder located anteriorly to the spinal column.
Internal Tail Anatomy
At the superior most part of the tail, we find the intestines. The intestines appear to be the same in nature as that of humans. Under a microscope the microvilli are clearly visible. The subject’s digestive tract follows the same pathway as humans, ending in an anal sphincter located on the anterior surface of the tail.
The subject has a complete lack of vagina, which is not a surprise when considering the nature of the anatomy. Due to internal structures, I suspect that the subject reproduces by ovuliparity. Although, as stated before, the absence of any known males of the species casts doubt on any conclusions drawn in this dissection. This inability to determine method of reproduction is frankly concerning, as it demonstrates a limit of what modern science can apply to the rules of Earth Beta.
It is currently unclear whether the subject has the ability to swap sexes as several species on Earth Prime have been shown to do, however if the subject can, it is through a different method than one already discovered as no signs of said ability were found.
The subject has no pelvic girdle, instead the spinal column extends to the distal tail, where it ends in a hypural. The tail contains 3 (three) muscles in the anterior compartment, and 3 (three) muscles in the posterior compartment. The muscles are separated into flexors and extensors which contracts to create the motion of the tail movement.
Upon observing the muscles in the subject, it’s shown that its striated skeletal muscle moves with the same crossbridge cycle that we utilize.
Acknowledgements
Dissection Notes of Subject #130 Volumes 1-6 by Dr. Barbra Cliffestone
Zoology of Earth Beta by Dr. Richard Wong
The Local Anomalies of Post-Collision Earth Prime by Dr. Amelia Roberts
Beginner’s Guide to Earth Beta by Charlie Ruan
Oceanic Currents in Earth Beta by Dr. Henry Culey