As explorers have pushed out from the core worlds, they have increasingly encountered species either unknown or poorly documented within the research literature. Most often this is due to the relative isolation of the planets where the species occurs – for example, little research has been done on the wampas of Hoth because the planet is both inaccessible and hostile to researchers. In other cases, research has been hindered by the apparent uniqueness of the specimen collected, such as the case of the so-called “Zillo Beast” of Malastare (Volpe & Titley, 2010). In yet other cases the limitations to study are characteristics of the creatures themselves, such as the secretive nature of the Dianogas of Vodran (Okorafor, 2017) or the extreme aggression of the Jungle Rancors found throughout wild space (Huddleston, 2016). Some unique species, such as the Sarlacc (Marquand, Kazanjian, Lucas, & McCallum,1983), exhibit all these traits – a large, aggressive, secretive species that are are sparsely populated throughout the galaxy – and warrant more careful study.
Like many rare and dangerous creatures, much of what is known about sarlaccs comes from folktales rather than empirical research. Because the creatures are both large and rare, specimens are often treated as geological features or mythical entities (Liu, 2017), and claims about them are treated with minimal skepticism. For example, early field reports (based on oral traditions) suggested that sarlaccs kept their prey items alive and in a torturous state of consciousness as they were digested “over a thousand years” (Marquand et al., 1983), a claim only recently challenged by modern research communities (Cavealos, 1999; Skywalker, 1983).
An essential step in dispelling these myths is to provide an adequate description of the species and locate its place in the phylogenetic tree. For most galactic species, these tasks are relatively straightforward. For example the Loth-cat of Lothal (Gilroy & Lee, 2014; Wallace & Bridger, 2014) presents behaviorally and morphologically as a feline or related carnivore. Sarlaccs, unfortunately, provide a more difficult cladistic challenge.
Brief Species Description
Sarlaccs are a species of burrowing creatures that are suspected to be invertebrates, though no comprehensive autopsy of any specimen has been conducted. Adult specimens bury their bodies deep in the ground leaving only an oral disc exposed. The oral disc is covered in concentric rows of radula, a type of “spine-like” ctenodont tooth (Nixon, 1995; Purchon & Clarke, 1978) that functions to prevent prey from exiting. Also attached to the oral disc is a series of tentacles, which the sarlacc can extend in a prehensile manner to wrap around prey, then retract and pull the victim into its mouth. The final notable feature of the oral disc is the presence of a two-part beak (Smale, Clarke, & Klages, 1993), which can be extended upwards from the oral cavity to grip prey. As prey items are drawn into the mouth of the sarlacc, they are believed to be injected with neurotoxins which result in paralysis and extreme pain.
The subterranean anatomy of the sarlacc is a topic of some debate. Ground Penetrating Radar imaging (Wong, 2000) has been attempted with limited success, and suggests that the full body of these creatures can extend hundreds of meters into the ground. Sarlaccs are believed to have multiple stomach cavities for digesting prey, though thorough anatomical studies have not yet been completed (Topps, 2015). Similarly, it remains unclear whether sarlaccs excrete waste through the mouth opening, or if they have subterranean orifices for expelling waste (Hejnol & Martindale, 2010).
Sarlaccs are opportunity predators, feeding on any organism that is unfortunate enough to wander within range of their tentacles. Although sarlaccs may appear stationary to the casual observer, they are known to move slowly from one location to another. Sarlaccs are believed to have a parasitic reproductive strategy (Topps, 2015); males are believed to attach onto females they encounter and feed on them, until the female dies. At that time, the male releases fertilized spores into the upper atmosphere. These spores may return to the surface of their homeworld, or may travel through space and colonize other worlds. Sarlaccs are believed to reach maturity at around 30,000 years of age; however further research is needed to confirm this observation and better document the sub-adult development of this species.
Sarlaccs as Cephalopods
Recent genetic research has revealed that sarlaccs share common ancestry with rathtars (Abrams, Kennedy, Burk, Swatz, Kasdan, & Kinberg, 2015), blixii (Dunlevy, Gilroy, & Melching 2011), and vixii (Lee & Michnovetz, 2011). These species, along with the dianoga, are known to be part of the Cephalopoda Class of the Phylum Mollusca. While Sarlaccs show significant similarities with other cephalopods, they also differ in important several important ways.
Cephalopods are marine invertebrates characterized by bilateral symmetry, horny beaks, complex eyes with a lens, a closed circulatory system, a central funnel that allows for propulsion (Lindgren, Giribet, & Nishiguchi, 2004), an internalized or absent molluscan shell (Gray, 2003), and the presence of multiple grasping tentacles emerging from a molluscan foot (Roper & Vloss, 2011). Some unique species of cephalopod, such as the nautilus and the blixus, have retained external shells.
Many cephalopods are also known for their unique ability to change color in response to environmental stimuli or for communication purposes (Prager, 2010; Ordinario et al., 2017). Many cephalopods also possess the ability to inject venom into their prey through their beaks, causing paralysis and death (Cooper, 2009; Cooke et al., 2015).
Like other cephalopods, sarlaccs clearly possess bilateral symmetry (at least in the visible portions of the organism), horny beaks, a closed circulatory system, a central funnel, and multiple grasping tentacles. Sarlaccs are not known to have any external shell, and the presence of an internal molluscan shell is unconfirmed at this time. However, sarlaccs appear to differ from traditional cephalopod morphology in two significant ways. First, the mouth of the creature is disproportionately large to the rest of the organism, with tentacles that are disproportionately small when compared with other cephalopods. Second, and more unusually, sarlaccs appear to lack the presence of a complex eye.
Behavior & Reproduction
On Earth, all cephalopod species are marine. They inhabit all levels of the water column, from the well lit surface to well past the limit of visible light. Cephalopods are known to be among the most intelligent of the arthropods, with finely developed brains and nervous systems. As a result, they are known to have richly developed social communication (Boal, 2016), problem solving (Richter, Hochner, & Kuba, 2016), and reasoning abilities (Mather & Dickel, 2017). Combining their intelligence with their excellent underwater agility, cephalopods are one of the most aggressive predators in the ocean ecosystem. Cephalopods are generally considered to be sight hunters, though they may also use tactile sense to detect prey in the water when visibility is limited (Villanueva, Perricone, & Fiorito, 2017). Lacking a protective exoskeleton, most cephalopods rely on their agility and camouflage for protection; however some species are also capable of expelling ink to cloud the water and further aid in escape (Derby, 2014).
Cephalopods follow an r-selection reproductive strategy, meaning they lead relatively brief lives during which they experience rapid growth. With the exception of octopi, reproduction is achieved through external fertilization (Fernández-Álvarez, Villanueva, Hoving, & Gilly, 2017), with large numbers of eggs then deposited on the ocean floor. While some species do protect their eggs (Robison, Seibel, & Drazen, 2014), adults of most species die shortly after successful reproduction and do not care for their young (Vidal, 2014). After a brief larval stage, young take the form of small adults and rapidly grow to maturity.
Sarlaccs appear to exhibit drastically different behavioral and reproductive strategies. Like almost all recently discovered galactic cephalopods, the sarlacc is terrestrial, and often lives far from large sources of water or on planets regarded as deserts. Sarlaccs are not known to engage in complex communication, problem solving, or reasoning. Rather than actively hunting their prey, they rely on potential food items to wander into the range of their tentacles or otherwise stumble into the oral cavity. Reproductively, sarlaccs appear to rely on a combination of internal fertilization followed by spore release and post-reproductive mortality, which presents a major departure from other known cephalopods.
Sarlaccs as Cnidarians
Curiously, there is another group of organisms whose morphology, reproduction, and behavioral patterns closely mimic those of the sarlacc. These are the sea anemones, which occur in the Phylum Cnidaria and Class Anthrozoa.
Anemones are aquatic invertebrates characterized by radial symmetry and the presence of a single orifice used for both feeding and excretion, which is surrounded by tentacles that bear cnidocyte cells (Babonis & Martindale, 2014). Anemones have a polyp body structure, which is characterized by a pedal disc that attaches them to their environment, a body trunk which contains the internal cavity, and an oral disc lined with tentacles. Unlike the cephalopods, anemones lack beaks, eyes, circulatory systems, shell structures, or complex propulsion systems. They also lack the presence of distinct teeth or similar structures.
This general structure bears at least superficial resemblance to the morphology of sarlaccs. Both rely on an oral plate lined with tentacles to entrap prey, and then draw them into a central gastrovascular cavity for digestion. However, sarlaccs appear to have greater tissue complexity and more morphological features than are observed in anemones.
Behavior and Reproduction
Unlike the highly intelligent cephalopods, cnidarians lack any centralized nervous system, and have only primitive contractile microfibers in place of muscles (Jahnel, Walzl, & Technau, 2014). Although they lack the strong swimming anatomy of cephalopods, anemones are capable of locomotion, and this can be quite rapid. However, for most of their lives anemones are relatively stationary, instead relying on their stinging cells for both feeding and defense. When an anemone’s victim comes in contact with the cnidocyte cells that line each tentacle, the cell fires a stinging capsule called a nematocyst. This releases fast acting venom into the potential prey item, causing paralysis, tissue damage, and beginning the digestion process (Jouiaei, Yanagihara, Madio, Navalainen, Alewood, & Fry, 2015). When prey items are paralyzed, they are then drawn through the mouth and into the gastrovascular cavity, where their nutrients are absorbed. When digestion is complete, the trunk of the anemone contracts to force the waste out of the oral orifice.
Cnidarians have a relatively simple life cycle. Males release sperm from their oral cavities, which in turn cause females to release eggs from their oral cavities (Bocharova, 2016. Fertilization can occur either within or outside of the oral cavities, and in hermaphroditic species and individuals, self-fertilization is not uncommon (Armoza-Zvuloni, Kramarsky-Winter, Loya, Schleisinger, & Rosenfield, 2014). In addition to sexual reproduction, many anemones can reproduce via parthenogenesis, (Larson, 2015), budding, or longitudinal fission (Bocharova & Kozevich, 2011). When parthenogenesis or sexual reproduction occurs, eggs turn into larvae, which in turn settle on the sea floor and become new anemones. If undisturbed, anemones can have remarkably long lifespans; in some cases individuals are believed to have lived over one hundred years (Daly, Chaudhuri, Gusmao, & Rodriguez, 2008).
Sarlacc behavior and life cycles are remarkably similar to those of anemones. Both rely on a strategy of opportunistic feeding from a relatively stable location. In both cases, prey items are ensnared, envenomated, and drawn into a stomach chamber for gradual absorption. Both sarlaccs and anemones are capable of gradual locomotion, and both rely on environmental currents to disperse fertilized eggs. Unlike the short lived cephalopods, both anemones and sarlaccs can live for centuries at a time.
As observed above, sarlaccs don’t seem like they fit well with other extant cephalopods or cnidarians. However, as noted above, genetic evidence does link them to the cephalopod genus. Researchers therefore must consider two hypotheses:
- Sarlaccs come from a branch of cephalopods that diverged early and evolved for unique terrestrial and space-based lifecycles.
- Sarlaccs come from a branch of cephalopods that diverged late and underwent substantial physiological changes due to evolutionary pressures.
Both hypotheses present some compelling evidence. If sarlaccs diverged early, they might predate the evolution of complex eyes, rapid locomotion, defensive sprays, and sophisticated communication. If sarlaccs instead diverged later, then we might attribute the loss of complex eyes and locomotion to environmental pressures, a process known as regressive evolution (Protas, Conrad, Gross,Tabin, & Borowsky, 2007). In our second hypothesis, we might attribute the transition from free-moving creatures to sedentary, burrowing creatures to costs associated with becoming terrestrial megafauna; this would not be unlike the major lifestyle and anatomical changes experienced by cetaceans as they regressed into aquatic forms (Fordyce, 1980).
Without sufficient genetic data from sarlaccs to assign them a place in cephalopod phylogeny through computational means, we must instead examine the sequence by which cephalopods evolved their modern traits. In doing so, we can evaluate whether the early or late-divergence hypothesis is most reasonable. Thankfully, the existence of a rich fossil record (Switek, 2015), embryological research, and molecular studies of less dangerous species (Kroger, Vinther, & Fuchs, 2011), we have a sufficiently detailed understanding of cephalopod evolution to complete this task.
The sequence of cephalopod evolution from mollusks can be roughly summarized as starting with the development of a high, conical, chambered shell in early nautiloids. Next, the development of tentacles occurred, which was followed by the internalization of the shell. The subsequent minimization and loss of the internal shell occurred multiple times in the phylogenetic tree, and thus is not a strong predictor of the sarlacc’s time of divergence. Eventually, a series of splits occurred between the octopi and the the squid, which is noted primarily by molecular changes in the fossil record. It’s worth noting that throughout this evolutionary process, the existence of complex eyes, rapid locomotion, and some degree of beak were already present; these are traits passed down from further up the mollusk family tree.
With these considerations in mind, it seems increasingly unlikely that sarlaccs are the result of an early divergence from the cephalopod tree. Instead, it seems more likely that sarlaccs are members of a group of cephalopods that evolved from octopi. We suggest that octopi might evolve into a freshwater tolerant, dianoga-esque organism. As the species became increasingly amphibious, we suggest a divergence in forms with one branch tending towards more sedentary and opportunistic feeding (culminating in modern Sarlaccs) and another leading to more active predatory organisms (like modern rathtars and blixi).
However, this proposed classification should be treated as purely hypothetical. It fails to account for several unique characteristics of sarlaccs that likely significantly impacted evolutionary pathways, such as the species’ extended lifespan and low frequency of reproduction. Additionally, while genetic and fossil records can grant us insights into species classification based on earth history, the absence of intergalactic fossil and genetic data means that important evolutionary branches may be overlooked. As we continue to learn more about sarlaccs and other intergalactic cephalopods, it will be essential to revisit the classification of this truly unique species.