Introduction
This post is the final one of my two-part special on the sea creatures featured in Allie’s Return. If you haven’t read the first part, you can read it here. I will only be highlighting deep-sea creatures that I haven’t already covered in an earlier post. So, if this post doesn’t cover a creature you read about in the novel, you’ll find it in this post from the Oceania: The Underwater City deep-sea special.
While researching for the first novel, I discovered that there were too many amazing creatures of the deep to include in just one novel. So, in this one, I added some of the ones I didn’t have time for in the first novel. Although only four are highlighted here, the humpback anglerfish and the binocular fish are cool animals I just had to include.
The Giant Squid
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| By Gene Carl Feldman (oceanographer at NASA/Goddard Space Flight Center) [Public domain], via Wikimedia Commons |
The giant squid (Architeuthis dux) is the largest invertebrate in the world! Although the largest one ever found was 18m (59ft) long and almost 907kg (2,000lbs), the typical size is 10m (33ft) long and 200kg (440lbs)(7). With enormous eyes that measure 30cm (12in) in diameter, they are specialized to help them see in the deep. These eyes can see bioluminescence or even predators in the dark waters. The eyes connect through a highly developed nervous system to the squid’s complex brain inside the mantel. The main body of the giant squid is comprised of the mantel, which houses all of its organs(9) including two gills(8). The funnel extends from the mantle and is used in liquid jet propulsion(9). Like all squid, they have eight arms and two feeding tentacles. On each arm and tentacle, they have two rows of spherical suckers with finely serrated rings of chitin. They use these to grip their prey and use their tentacles to bring the prey up to their mouth to be eaten (8).
Elusive species, most of the research on them have been conducted on dead specimens. Only Japanese researchers have captured and taken photographs of a live one(7). Due to such little research being conducted on live specimens little is known about their behavior and life history beyond conjecture based on similar squid species(8). Yet, from the stomachs of dead specimens, their diet is known to consist of at least shrimp, other squid and it has been proposed that they may eat small whales(7). Cannibalistic, they will even eat other giant squid(9)! To eat their prey, they use a tongue-like organ called the radula which is covered in tiny rows of teeth(9). The radula is used to tear apart pieces of prey along with the beak so that the prey can be consumed(7).
Listed as least concern by the IUCN(10), the giant squid is known to have only two predators—the sperm whale and sleeper sharks(8). They live from 500 – 1,000m (1,650 to 3,300ft) below the surface(9).
To see a better picture of a living giant squid, click here.
Humpback Anglerfish
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| By Javontaevious at English Wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons |
The humpback anglerfish (Melanocetus johnsonii) is a rare anglerfish of the deep. Like all anglerfish, it exhibits sexual dimorphism. The females are around the size of tennis balls at 18cm (7in), but the males are small at up to 2.9cm (1.1in) or around the size of a jellybean(3). They live in tropical and temperate waters(2) in depths of more than 2,000m (6,600ft)(3). With no scales or pelvic fins and black in coloration, they are also known as humpback blackdevils(2). They have very light bones and hover in the water to await prey to be attracted to its lure. The males have no anglers, large eyes, small mouths, large nostrils, and muscles for swimming long distance(1).
Humpback anglerfish are unique among anglerfish as they are one of the few anglerfish species that does not mate for life. The males do not attach to the females for a long period of time but instead, attach only to mate and then leave to find another female(3). When the male finds the female, they use their hooked teeth to attach to her and drink her blood for sustenance during mating(1). Though the male joins to the female once he locates her, eggs are fertilized via external fertilization where the female releases the eggs into the water and the male releases the sperm which will then fertilize the eggs(3).
Similarities to other anglerfish include large mouths to help capture the limited amount of prey in the deep sea and large stomachs to accommodate whatever prey they do manage to swallow. Bacteria live in its lure and create the light it uses to attract their prey. Yet, they have a muscular flap they can use to close off the light to either hide or expose the lure. They eat crustaceans, fish, and anything else that can fit into its mouth(3).
If you would like to see a video of one swimming, click here.
Binocular Fish
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| Winteria telescopa From Brauer, A., 1906. Die Tiefsee-Fische. I. Systematischer Teil.. In C. Chun. Wissenschaftl. Ergebnisse der deutschen Tiefsee-Expedition 'Valdivia', 1898-99. Jena 15:1-432. |
The binocular fish (Winteria telescopa) is currently extremely underresearched. Almost nothing is known about this species besides its appearance. They are a bluish-black color with some silver on its head. They are known to grow to 15cm (5.9in) and live anywhere from 500 – 2,500m (1,640 – 8,202ft). They are found in the Atlantic, Indian, and Pacific oceans. The IUCN lists them as least concern and they are no threat to humans.
Hagfish Family Myxinidae
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| By Girard, Charles, 1822-1895;United States Naval Astronomical Expedition (1849-1852) [No restrictions], via Wikimedia Commons |
*Hagfish are about as primitive as chordate (vertebrate) life gets in the sea. In Allie’s Return, I referred to the creature as Myxine sp. because there wasn’t a name yet for the species referred to in the novel. This was for many reasons. One reason was because I could not find any research confirming a species in the Myxinidae family with any particular special enzymes in their gut. Another reason is because I wanted it to remain ambiguous. So instead of exploring the characteristics of any species of hagfish here, I’m going to look at Myxinidae as a family.
Myxinidae is the family that comprises of hagfish and their relatives. Hagfish may look like eels, but they are fish with no scales, no gut, and no fins except for a reduced caudal fin that merges with the main elongated body. They can have from one to sixteen pairs of gill slits on each lateral side. Instead of a jaw, they have barbels (like on a catfish) and rasping teeth along their tongue. Other physical features include a growth of up to 1.1m (3.6ft) and skin with gray or brown coloration. They are found in every ocean and inhabit the benthic region making them bottom-dwellers. They prefer temperate waters with soft bottoms down to 1300m (4,265ft). Some of the oldest fish in the sea, fossils of them have been found from 300 million years ago(5). Myxinidae have been found to be hermaphrodites or sterile. They lay a few eggs which will then grow into adulthood with no larval stage in between(6).
Scavengers, they feed on dead and decaying animals such as marine mammals that have sunk to the ocean floor(5). They have a slow metabolism and can survive for seven months without eating. If necessary, they can eat worms,(6) fish, or small crustaceans to survive(5). They use their sense of smell to find food and will then burrow into the prey using its rasping teeth and consume it from the inside out. If there are already holes in the organism, they’ll enter that way and eat it. Their role is extremely important in the marine ecosystem because they clean up a lot of decaying material at the bottom of the ocean. Without them, the ocean substrate would be littered with decaying carcasses(6).
One of the most popular known characteristics of Myxinidae are the slime they produce that covers their entire body. It is indeed very thick and slippery. It helps Myxinidae evade predators by making it hard for them to grab them and filing their mouths with so much slime that they have to spit them out(5). They have few predators, but some marine mammals and invertebrates will consume them. However, they run the risk of being suffocated by the excess of slime the Myxinidae produce(6).
As far as conservation, they are eaten in Asia as food and used for leather. Some populations are at risk of overfishing and nine species of Myxinidae have been listed as threatened due to overfishing and habitat destruction(5).
To watch a video of a hagfish from Smithsonian, click here.
Closing Thoughts
Every time I research creatures of the deep for my novels, I’m astonished by how little we know, even about iconic species like the giant squid. It amazes me that many of these creatures have been known to science for over a hundred years, but we’ve barely learned anything about them. My goal in these novels and in these blog posts is to share the little knowledge we do know and hopefully inspire others to learn about the ocean. Still, to make a great story and keep it exciting, I do take advantage of the gaps in our knowledge. Based on our limited knowledge of the deep-sea, I did take some liberties Allie’s Return with the hagfish relative. The relative was inhabited water deeper than the hagfish we know of today and exhibited some different physical characteristics. However, who knows what lies in the deep and what we may discover in the future. Our only hope is to keep exploring the deep and discovering what it has to offer.
References and Further Reading
(1) https://teara.govt.nz/en/photograph/5268/humpback-anglerfish
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