Origins of Thalassa’s Nesoi, Ceti, and Baleena

A procetid, the ancestor of modern whales, and the model for the Ceti on Thalassa. . They swam the seas and walked on land. on earth 40 million year ago. How did they end up on Thalassa?

As a marine biologist I am always spellbound watching whales on the open sea. Witnessing their majestic movements, they are the most marine of all creatures, but I never fully appreciated their origins until I researched the topic before writing SOT. I focused on the ancestors of cetaceans because they are super-cool and are a great hook to get people to read my book. They also use sonar and sing songs and thus are perfect to play a major part of the “songs” of Thalassa (but they are not the only ones).

Modern whales also play an important role in Polynesian (and Hawaiian) culture and have a tragic history of exploitation. For all of these reasons I used the Nesoi, Ceti, and Baleena as central figures in SOT. Please remember that these are not the same as their counterparts on earth for two reasons: first, they are of uncertain origin; and second, they have evolved on Thalassa for millions of years. For more on these amazing creatures you’ll have to wait for my next book, Songs of Hina.


Illustration of Dorudon, a prehistoric whale ancestor, and model for the Nesoi. Source: Mikkel Juul Jensen.

So to begin, imagine an ocean with no whales, no dolphins, and no porpoises. If you could travel through time and swim in Earth’s warm Tethys Sea of 50 million years ago (mya) you’d by startled by the early ancestors of whales — the walking whales; the model for the Nesoi.

Whales and their relatives, the cetaceans, are related to terrestrial (even-toed) ungulates like the hippopotamus. They are all descendants of semi-aquatic animals that invaded the empty sea in Eocene times to prey on rich marine resources (and the absence of marine reptiles). To truly understand the story of cetaceans we need to place their ancestors, deduced from fossil evidence, in the context of continental drift and the formation and fate of the Tethys, and (natural) long-term climate change. For the full story, go here.

Drivers of Whale Evolution: Continental Drift and Climate

Fossils of the walking whales show they evolved in the Tethys’ swamp-like seas then spread through what would become the Mediterranean and Caribbean seas and eventually to the Pacific coasts and worldwide oceans. Much of their success was driven by climate. In the beginning, when the ancestors of whales invaded the sea, it was super warm –the warmest seen in the last 65 million years. But 15 million years later, Earth shifted to a cool, ocean-rich ice age. It was the perfect climatic driver for the success and spread of early cetaceans.

To help you understand the evolution of cetaceans, and the appearance of the major species in SOT, I’ve included a brief illustrated description of their journey to global prominence on earth.


Pakicetus — the first cetacean on Earth (49 mya)

Illustration of Pakicentus, the mammalian ancestor of all whales that invaded the shallow Tethys sea 49 million years ago. Source: Lucas Lima, https://252mya.com.

Pakicetus was a dog-sized, mostly terrestrial mammal that occasionally hunted fish in the shallow Tethys sea. It had several unique characteristics adapted to a partial aquatic existence: upward looking eyes, thick bones (which assist in floating), and a thickened skull bone to improve underwater hearing. This species was hugely successful in exploiting the rich marine resources of the shallow seas. As it became adapted to a more aquatic existence, over a million years it gave rise to another more ocean-oriented species.


Ambulocetus — the walking whales (48 mya), the model for the Nesoi

Fossils of Ambulocetus were first found in Pakistan in 1994 and made headlines as the “walking whale” due to its combined aquatic and terrestrial features. Why Pakistan you might ask? If you go back to the Eocene, the continent that would become India was surrounded by ocean and was slowly rafting towards Asia. As got close it created the warm, shallow, island-rich Tethys Sea which persisted for millions of years. It was the perfect setting for a mammal to invade the sea. Today, the fossils of early cetaceans are found in the continental shelves of the former Tethys, which are exposed in modern day Pakistan, Afghanistan, and in even in the Himalaya mountains; all former seafloor that was created by India’s collision with Asia.

Illustration of the continents during the early Eocene.

Ambulocetus were up to 10 feet long and it’s crocodile-like shape included an elongated snout with upward-facing eyes. Studies suggest it was mostly aquatic, using it’s front and hind legs and tail to swim, but occasionally walked on land to drink freshwater and give birth. It was a big change from Pakicetus and one that supported the eventual spread of its descendants out of the Tethys corridor.

The Neoi in SOT are based mostly on these walking whales with a few modifications. Unlike what we know about these ancestral species , the Nesoi were capable of a unique set of traits due to their millions of years of evolution on Thalassa: 1) sonar for navigation (their “clicks:” and “creaks”); 2) the ability to communicate by whistling in air; and 3) the ability to sing beautiful songs like baleen whales to communicate to each other and to other creatures on the planet (they could even be heard in space). Given these abilities their heads would have different morphology than Ambulocetus to be able to create and receive sonar, whistles, and songs. Their whistles are based on Silbo Gomero, a whistling language used by humans of La Gomera in the Canary Islands to communicate by whistles across the deep ravines and narrow valleys that radiate throughout the island. Their sounds can be heard up to a distance of 3 miles (Wikipedia)


Procetids spread across the Tethys (47-39 mya), the model for the Ceti

Procetids were a big step towards a more aquatic existence than the walking whales but with their hind legs they could still walk (and give birth) on land. But over 8 million years on earth multiple adaptations arose to a more-marine existence with some species walking on land and others being fully aquatic. Major changes include their eyes shifting to the side for better aquatic vision, their nasal openings moved closer to their eyes, and their ears became more adapted to underwater hearing. These major adaptations were key to the ultimate success of these cetaceans.

I used the procetids as a model for the Ceti on Thalassa, the first one Sage encounters in the cave of light. Part of including the Ceti was to show that the ancestors of the Nesoi had diversified on Thalassa, as they would have across an ocean mostly devoid of large animals. Based on what we know on Earth, over millions of years on Thalassa I believed the Ceti would exploit large mantis squid in the deep seas and submarine canyons of Thalassa. As such, they would move away from a land-based existence and become more fully aquatic and give rise to critters more similar to our modern whales, but with a twist (no pun intended). Expect more about the Ceti in the next book.


Modern whales emerge as Climate Shifts– (33-28 mya), Model for the Effects of Hina

On earth, the ancestors of toothed and baleen whales diversified and eventually diverged as the world’s climate cooled and opened up new opportunities for their ancestors, the basilosaurids, the descendants of procetids. Shifting continents 34 mya on earth created large-scale changes in ocean currents and temperatures that coincided with this diversification. Principle among them was the isolation of Antarctica and the openings of the Tasmanian Seaway and the Drake Passage resulted in the largest current on the planet, global cooling, and the Antarctic circumpolar current that created the richest marine resources on earth.

Illustration of development of circumpolar Antarctic current in late Eocene. From Blakey (2020), Geology b102, Historical Ecology.

I included the same process in the history of Thalassa where the arrival of Hina warmed the planet from increased volcanism, which raised sea level , and opened up two circumpolar currents, just as did on earth. As discussed in the book, the new currents created the perfect whale feeding grounds: Cetacean heaven! These changes helped create the next phase of diversification for the ceti and new species on Thalassa, as it occurred on Earth.

Baleen whales tap the world’s plankton (36 mya-present), the model for the Baleena (and others to come)

On earth, the emergence of crown-shaped teeth 30 mya show an early transition from teeth to baleen, the filter-feeding system inside the mouths of all modern baleen whales. Filter feeding is beneficial and allowed baleen whales to tap huge planktonic energy resources, such as Antarctic krill, which eventually resulted in the massive body size of modern species.

The jaws and serrated teeth of Coronodon, a toothed mysticetes from the early Oligocene (30 mya). The serrated teeth may have been an early form of suction feeding, which led to the development of baleen.

Early species were suction feeders, and may have used their serrated teeth to feed on plankton. As the planet cooled even further, baleen, sheets of fingernail-like teeth hanging from the roofs of their mouths, evolved and baleen whales diversified into many species, including the modern day skimmers (e.g., right whales), bottom feeders (e.g., Gray whales), and the roqual whales, which are lunge feeders (e.g., humpback and blue whales). Their hearing organs became adapted to send and receive long-range sounds, which became the basis for the melodic songs of modern species used for communication.

Mouth of a Gray whale with 300 baleen plates attached to the roof of their mouth to strain food from water and sediment. Photo by Christopher Swann/Minden Pictures.
Blue whales lunge feeding. Try to picture Sage’s sight of the Baleen feeding in a similar way but in a spiral fashion.

Toothed whales exploit the deep sea (34 mya-present), the Model for Other Thalassa Cetaceans

As baleen whales evolved ways to tap into the ocean’s abundant plankton, the ancestors of toothed whales developed sonar (echolocation) and became the largest predators on the planet. Echolocation involves emitting a series of clicks at varying frequency using an expansion of the head to send sound waves, bounce them off potential prey or surroundings, and receive the signals with their elongated lower jaw. This key adaptation made them more efficient predators and allowed them to dive deeper in search of food which opened up the rich resources of the deep sea on earth (e.g, squid).

Illustration of echolocation in dolphins, from Lubis (2016).

On earth, the success of these early species eventually gave rise to dolphins and porpoises, sperm whales, killer whales, and beaked whales. On Thalassa, recall that the team from the Duke only had a short period of time (and one submersible dive) to explore its oceans. The open ocean, the deep sea, and the mysterious nearshore splashes Sage observed, are all potential sources of new species to be found in the next book, Songs of Hina.

Interestingly, early sperm whales on earth, such as Livyatan, hunted other whales with their monster teeth. Could be a cool critter to include in the next book. Let me know what you think.

Livyatan, the sperm whales that hunted whales. Left: Livyatan jaws, center: illustration of mouth with teeth; right: preying on a whale.

Cetaceans Status and Conservation on Earth

Clearly, cetaceans have a spectacular evolutionary history of successfully invading the sea. Within 15 million years they went from a terrestrial lifestyle to a fully marine existence and are now the most aquatic and widely distributed of all marine mammals. Similar invasions of the sea by the marine, but coastal, manatees and dugongs (40 mya), the semi-aquatic seals and sea lions (24 mya), and the coastal sea otters (2 mya) and polar bears (130k) occurred but with less success.

From Cressey, 2015.

Tragically, these magnificent animals, have a dark history of human exploitation and most all are on the UN’s endangered species list. Pre-human global cetacean populations were…well, we don’t know and never truly will. Based on genetics, current populations of the remaining great whales are estimated at >10% of their pre-contact populations sizes in most species. Prior to whaling, Antarctic blue whales were thought to number about 250,000 individuals but were reduced to fewer than 400 animals by 1972 — about 1% of its former populations size (Roman et al., 2014). As quoted by Halina in SOT, researchers estimate that in the 20th century alone, three million whales were killed by the whaling industry (Cressey, 2015).

Without a doubt, these magnificent, intelligent animals with their beautiful songs, amazing sonar capabilities, and role as ecosystem engineers which enhance the productivity of the world’s oceans, deserve our utmost respect and the highest level of protection. In an effort to promote their conservation, this is the principle reason they were included in SOT. Is Milo and Moshe’s treatment of the Nesoi typical of what we would expect after we discover a new species on a virgin planet? I leave you with this question and ask you to ponder the wisdom in Sage’s talk at the Oceanarium.


References and further reading:

  • Cressey, D. 2015. World’s whaling slaughter tallied. Nature 519: 140-141.
  • Gingerich, P. 2012. Evolution of Whales from Land to Sea. Proceedings of the American Philosophical Society. 2012 vol: 156 (3)
  • Lambert, O. et al. 2019. An Amphibious Whale from the Middle Eocene of Peru Reveals Early South Pacific Dispersal of Quadrupedal Cetaceans. Current Biology 29, 1–8, https://doi.org/10.1016/j.cub.2019.02.050.
  • Lubis, M. Z. 2016. Behavior and echolocation of male Indo-Pacific Bottlenose dolphins. In: Male Info-Pacific Bottlenose Dolphins Captive
  • in Indonesia. Chapter: 3, Publisher: Lap Lambert Academic Publishing, Editor: C. Evans.
  • Marx F, Fordyce R. 2015. Baleen boom and bust: A synthesis of mysticete phylogeny, diversity and disparity. Royal Society Open Science, 2015 vol: 2 (4)
  • Marx F., Hocking D, Park T, Ziegler T, Evans A, Fitzgerald E. 2016. Suction feeding preceded filtering in baleen whale evolution. Memoirs of Museum Victoria vol: 75 pp: 1447-2554.
  • Marx, F., O. Lambert, and M.D. Uhen, editors. 2016..Cetacean Paleobiology (TOPA Topics in Paleobiology). Wiley Blackwell. 319 pp.
  • Roman et al. 2014 Whales as ecosystem engineers. Front Ecol. Environ. 12(7): 377–385, doi:10.1890/130220.
  • Steeman M, Hebsgaard M, Fordyce R, Ho S, Rabosky D, Nielsen R, Rahbek C, Glenner H, Sørensen M, Willerslev E. 2009. Radiation of extant cetaceans driven by restructuring of the oceans. Systematic Biology. vol: 58 (6) pp: 573-585
  • Thewissen, J. G. M. 2014. The Walking Whales: from land to sea in eight million years. University of California Press. 245 pp.
  • Uhen, M. 2010. The Origin(s) of Whales. Annual Review of Earth and Planetary Sciences, vol: 38 (1) pp: 189-219.

Life on Thalassa

How Earth might have look after 4 billion years of evolution, with Stromatolites (cynaobacteria and perhaps green algae) dominating the coastlines. Multi-cellular life was just starting to appear on the planet. By comparison, Thalassa is 1.8 billion years old in SOT.

First contact! What might life look like on other planets? We may not be far away from that experience. Although we have discovered thousands of exoplanets in the last decades we know of only one planet with life: Earth. So, as a marine biologist, life on Thalassa was created using the scientific foundations and evolutionary history of what we know about primitive life on Earth, with some added twists.

Since we don’t know what life might look like on another planet, it is possible some alien life will be similar to earth’s life in overall appearance and form due to the constraints of an organism’s functional anatomy, physiology, and its cellular and genetic foundations, which I assume is based on something like DNA and RNA. My bias and that of almost all science fiction writers, is that we tend to look at life on other worlds through a water-borne, carbon-based lens and life on other planets may be fundamentally different than Earth (see Irwin and Schulze-Makuch, 2011). At any rate, I surmised life on an ocean planet would be similar to our planet in basic life forms, but ecologically unique due to the differences of a younger, ecologically different setting.


Primitive Life : the “fronds”

The earth is very old, 4.6 billion years to be precise: an immense amount of time that is difficult to comprehend. The truth is that after the earth had a chance to settle down from its violent birth, which included coalescing from planetesimals, violent volcanic eruptions, a collision with a Mars-sized object that created the moon, and 300 hundred millions of years of bombardment by massive asteroids and comets, primitive life evolved relatively quickly and appeared after 1.1 billion years. However, it took another 3 billion years for multicellular life to begin. Thus, most of our planet’s history has been dominated by single-celled organisms such as archaea, bacteria, including cyanobacteria (blue-green algae), and single-celled creatures (eukaryotes). I imagine that Thalassa had a similar early history but an accelerated rate of evolution.

ediacaran_1

Depiction of Ediacaran Fauna, showing rangeomorphs and other multicellular species which was model for life on Thalassa.

Most scientists look to the “Cambrian Explosion” for the beginning of multi-cellular animal life, and rightfully so. It was at that time, about 540 million years ago (mya), that an amazing diversity of animals appeared to explode on the scene, or at least in the fossil record. First documented in the famous Burgess Shale of British Columbia and discussed in Stephen J. Gould’s incredible book Wonderful Life, complex animals appeared to burst onto the planet in an unparalleled record of animal diversity with most of the modern animal groups intact. But there is an older, and more recently discovered era, the Ediacaran, that actually represents the earliest appearance of complex life. And it’s a fascinating era with many puzzles. Chief among them are the Rangeomorphs, an enigmatic group of organisms that were ubiquitous in fossil assemblages over 580 mya, 40 million years before the “Cambrian explosion.” The rangeomorphs were the basis for the “fronds” on Thalassa.

Ediacaran fossil assemblages are common at only a few places:  Newfoundland, Arkhangelsk Russia, Namibia, Charnwood Forest in England, and at their namesake in the Ediacaran Hills in South Australia. Although there are differences, each site shows a common architectural organization of a group of primitive critters that lived for over 30 million years. To call them invertebrates is probably presumptive; they may not even be animals. Their unique frond-like fractal body plan consisting of petals branching off a central axis and occurs across dozens of taxa.

Although they were found in shallow water environments, their structure precludes filter feeding and they were widespread in deep water indicating they may have fed on dissolved organic matter which was common in the microbial-dominated Ediacaran seas and possibly in the early evolutionary history of any ocean planer. In some cases, they occurred at densities and distributions similar to modern-day invertebrate communities with major diversity patterns that exploited resources at different levels above the seafloor.  Early forms were simple and prostrate while more derived forms showed a complex, fractal-based structure elevated successively elevated above the substrate. These patterns indicate species may have been adapted to variation in water flow.

The leaf-like rangeomorphs, some of which grew to 2 meters in height, showing what Thalassaian seas might have looked like. Photo: Richard Bizley

In a recent review, (Liu et al., 2015) examined the ecology of the Ediacaran organisms, including the Rangeomorphs. Their conclusion: We don’t really know what they were or how they functioned. Here’s what they concluded:

  1. They probably aren’t related to any modern marine life: they are likely an early evolutionary experiment in multicellular life and a stem-group branching off just before or after the divergence of animals and fungi (Erwin and Valentine, 2013).
  2. Their frond-like morphology is unique: their fractal-based segmented morphology suggests their surface area: volume ratio was constant, unlike modern animals where it decreases with size. Thus, their bodies may have been filled with inert substance such as water or sediment to maintain thin tissue contact with the environment  (Laflamme et al., 2009).
  3.  They were common in both shallow- and deep-sea environments: therefore, they could not have used photosynthesis and had no obvious structures for filter-feeding so their feeding strategy was enigmatic.
  4. They may have fed passively: one hypothesis is they feed by osmotrophy (Laflamme et al., 2009) which involves simple absorption of dissolved organic carbon (DOC) from seawater. DOC may have been 2-3 orders of magnitude higher in the microbial-dominates seas of the Ediacaran and a common source of energy. Their constant surface area: volume area supports this possibility.
  5. They may not have been animals: one hypothesis suggests they were fungi (Erwin and Valentine, 2013), perhaps even lichens (Retallack, 2014), and these were early adaptations to primordial seas and shores.
  6. In a more recent study (Lui and Dunn, 2020) colonies of rangeomorphs have been found to be connected by small filaments, and hence were colonial.

Based on this science, I created the “fronds” on Thalassa which varied from small shallow-water balloon-like structures to deeper-water, more complex kelp forest-like structures. When touched, they quickly disintegrate into sand, which is one hypothesis for the anatomy of the rangeomorphs. But as with all life on Thalassa, I created them to be symbiotic with bacteria which helped them live off both sunlight (in shallow water) and DOC (in deeper water). Although not stated in the book, I believed the fronds shared the same cellular components as the lichens and hence were both fungi and algae, which is why they dominated the seas.


The Jellies, Sheets, and “Anemones”

Jellyfish, or the medusa-like life phase of cnidarians (like anemones and coral, are primitive and ancient animals so I included them in Thalassa’s seas. However, unlike Earth’s jellies, I created the “sheets” as large simple animals that used stinging cells, like the cnidocytes of jellyfish, as protection and a way to capture prey. Among the Cnidaria, cnidocytes can induce a range of responses from deadly stings, to stickiness, to slight numbing.

Jellyfish, the model for the “Sheets,” have two layers of tissue with a soft “jelly-like” middle layer.. Photo: Sharon Ang, Pixabay.

I decided to create a species that slowly becomes more deadly over time, allowing a prey item to not pull back at first encounter but eventually become immobilized and then consumed. The teachings of the Nesoi shows that they have had past encounters and remember their lessons. Sage tried to avoid the sheets based on her first encounter with a small one (which stung hard, like on Earth) but was helpless against the all encompassing larger ones. On Earth many species of jellyfish bloom during certain times to become very abundant and cover the surface of the ocean.

Moon Jelly fish blooms. Photo: Morgan Bubel.

I limited the distribution of the sheets to calm, inland waters as their simple structure would be easily torn apart in waves and during extreme tides, hence their absence after Thalassa’s tidefall. As like jellies on Earth, the sheets can harbor symbiotic bio-luminescence organisms which cause them to “glow” in the night.

Anemones are early life forms related to the sheets but I used their appearance to trick Sage into thinking that because they looked like anemones, they were the normally harmless anemone. Instead, they were a worm-like animal similar to the Bobbit Worm. These worms are notorious for their vicious and lighting-fast predatory attacks, as seen in the book.

A tube anemone I(left) and (right) a Bobbit worm in action.


Complex Life: Blobs, Marble Sponges, Pika, and Mantis Shrimp

During the Ediacaran, we also saw the appearance of species that indicate the ancestors of modern animals were clearly present, including the ancestors of amoeba, sponges and ctenophores. All of these are in SOT as the floating amoeba-like “blobs,” marble sponges, and the drifting white marbles. Our sponges are composed of millions of cells with tails (flagella) that drive water through their bodies for feeding and are related to free-living, single-celled choanoflagellates. One hypothesis is that choanoflagellates aggregated to form sponges. Based on that, I created the white marbles and marble sponges to be related, with marble sponges being an aggregation of white marbles, another example of symbiosis.

The floating amoeba-like red-orange “blobs” Georgia observes in the submersible were based on a symbiosis between shell-less snails, or sea slugs, and their internal chloroplasts they contain from eating plants. They are an animals that can live off sunlight. In their lab on the Duke, Sage and Georgia observe one transform from a single-celled amoeba to a slug-like animal with a head.

The green sea slug Elysia, model for the “blobs.” Symbiosis with chloroplasts it gets from eating plants allows it to live off of sunlight. Photo: Patrick Krug.

On Earth during the Ediacaran there were other invertebrates, such as Kimberella, a putative ancestral mollusk, indicating that bilaterally symmetric animals were likely on the scene, so they also appear in the book. These species eventually gave rise to our vertebrate ancestors in the Cambrian period 20 million years later. Early primitive ancestors of vertebrates (like fish) include Pikaia and our modern-day lancelets, like Amphioxus.

Pikaia is, of course, is the namesake for “Pika” in SOT, the principal dietary source for humans and the Nesoi. Lancelets feed using a ring of small projections (cirri) around the mouth which drive plankton-laden water over their gills slits and trap food for consumption, I created Pika to be similar but instead have a row of pores and cirri spirally arranged along their body that drive food-laden water through their pores and into their bodies. I created their (and other animals) spiral motion to be unique to Thalassa and a consequence of spirally-organized plankton in the water column. Ultimately the spiral motion in many animals is due to Thalassa’s small size, high rate of rotation (18 hr days) which results in a high Coriolis force.

Mantis squid were created as the principal indigenous marine predator. Their morphology was based on a combination of several creatures on Earth: 1) a crustacean-like segmented head with antennae, eyes, mouthparts, and lighting-fast appendages like a mantis shrimp; 2) a body and tentacles (including light organs) of a deep-water giant squid. Their behavior as sit-and-wait predators is consistent with many octopus, as is their use of blinking lights and camouflage to help them blend in with their surroundings.


Lichens

Lichens on Earth are a symbiosis between fungi, which live on organic matter, and algae which live off of sunlight through photosynthesis. Because they are among the oldest living symbiotic organisms, perhaps older than 400 million years and extending back into the Ediacaran, I used them as a model for the primary organisms dominating land on Thalassa. Another reason is that lichens are super-tough and live in extreme environments like the freezing tundra, hot deserts, and even in toxic waster dumps. They can even live inside solid rock, growing between the grains (Wikipedia). Amazingly, a European Space Agency experiment discovered that they can survive in the harsh conditions of space.

Thus, it is possible they would have evolved in a similar but somewhat different form on a planet like Thalassa and have colonized land. Given their extreme habitats on Earth, they could survive Procyon’s glare because it is a larger, brighter F-type star that emits higher levels of cell-damaging (UV) ultraviolet light. A study showed that DNA molecules under the glare of an F-type star such as Procyon would suffer 2 to 7 times more damage from UV light compared to that inflicted by our Sun, something a symbiotic lichen might survive.

Fruiting bodies of lichens, the base of the slug-bug-chimera food chain.

I based the growth forms of lichens on Thalassa on those found on Earth. Most were encrusting, and covering the rocks, but some were also crustose (which Sage tried to eat) or branching. Because they were photosynthetic I created them to be red, orange, or yellow because Procyon’s light output would be in higher wavelengths and their pigments may be different than our green plants (Kiang, 2008). The base of the slug-bug-chimera food chain were the fruiting bodies of lichens, which occur when they reproduce.

Slugs, and Bugs, and chimera, oh my!

One of the hardest parts of the books was coming up with an idea of what life would be like on land on Thalassa. As the ocean buffers extreme temperatures and UV light it was more likely to have rich life, as it does in SOT. But land is much harsher and the first colonizers of land on Earth failed several times before they were successful (McGee, 2013). But when the cycles came into the plot, along with clouds and rain, I developed an idea based on periodic cicada life cycles. Although they are different, period cicadas emerge from the ground every 13-17 years in a population explosion that swamp out predators so enough survive to make it to the next generation. I hypothesized that a similar adaption could occur during the two-year rain cycles resulting from Hina’s orbit.

Every food chain needs a base, a source of primary production. In SOT I used the fruiting bodies of lichens , which contain algae, as that source. From there other animals consume them, and then their predators eat them, and so on up the chimera. The slugs and bugs were based on primitive invertebrates from the Cambrian period. Here’s some of the primitive species (mostly Cambrian) that inspired the slugs and bugs in SOT.

Chimeras had another origin and were inspired by the “Grendel” in Niven, Pournelle, and Barnes Legacy of Heorot (1987) and the POV they used in the book. If you haven’t read the book you should as it is fascinated to look at how the first colonizers of a planet might deal with an alien life form. In SOT, the chimera, which by definition is a “mix” of several different features, was constructed using several Earth-based life forms including an arthropod and squid. It was designed to be a relative of the mantis squid that invaded land by colonizing rivers and burrowing the in the mud until the massive rain events. On Earth, most animals that colonized land first adapted to lakes, ponds, and rivers, then migrated onto land. Like the Grendel, chimeras can only survive out of water for a short period of time and must return to their river lair to survive. From there, they launch horrendous attacks on the early human explorers from the Proteus and the Duke, threatening their existence. Although, as you can see on the cover of the book, the Grendel looks quite different than a chimera as envisioned in SOT, the general idea of a river-based creature attacking the first explorers of Thalassa is a major feature of the plot.

The idea of burrowing in the mud for long periods of time then emerging with the rains follows the typical lifestyle of many desert animals, like the spade foot toad. They are adapted to dehydrating during long periods of intense heat and lack of moisture and rehydrating when the rains return, just like the chimera.

In summary, this is some of the science behind the basis for life on Thalassa. I document the cetacean-like animals in another section. Most all life is based on earth ecology and evolution with changes due to the unique environment and age of Thalassa. There is plenty more to learn, just check out the references here and explore the overall reference list.

References:

  • Erwin, D.H., and Valentine, J.W. 2013. The Cambrian Explosion: The Construction of Animal Biodiversity. Roberts and Co., Greenwood Village, CO. xii + 406 p.
  • Gould, S. J. 1990. Wonderful Life: The Burgess Shale and the Nature of History. W. W. Norton & Company, New York, NY. 352 pp,
  • Irwin, L. N. and Schulze-Makuch, D. 2011. Cosmic Biology: How Life Could Evolve On Other Worlds. Praxis Publications Inc , 337 pp.
  • Lumbsch, H. and J. Rikkinen. 2017. Evolution of Lichens. In Chapter 4, The Fungal Community: Its Organization and Role in the Ecosystem, Fourth Edition. Edited by John Dighton, James F. White. 597 pp.
  • Kiang, N. 2008. The color of plants on other worlds. Scientific American, April 2008, pp. 48-55.
  • Liu, A. G., C. G. Kenchington and E. G. Mitchell 2015. Remarkable insights into the paleoecology of the Avalonian Ediacaran macrobiota. Gondwana Res. 27: 1355-1380.
  • Liu, A.G. and F.S. Dunn. 2020. Filamentous Connections between Ediacaran Fronds. Current Biology 30, 1–7, https://doi.org/10.1016/j.cub.2020.01.052
  • Retallack, G. J. 2014. Precambrian life on land. The Paleobotanist  63(2014): 1-15.
  • Valentine, J.W. 2013. 2004. On the Origin of Phyla. University Of Chicago Press. 608 pp.
  • Xiao, M., S. and M. Kowalewski. 2009. Osmotrophy in modern Ediacaran organisms. Proc. Nat. Acad, Sci. 106(34); 14438-14443.