Theoretical Biology Model (Deep Sea Gigantism) 2024
Work in progress
Resources: Report (Download) | Pelagica (open beta)
Project context. This project originated in IB 494 — Theoretical Biology at UIUC (Spring 2024, Prof. James O’Dwyer). The course focused on building biological models, with an emphasis on disease modeling and food-web dynamics using R. This project investigates the phenomenon of deep-sea gigantism (DSG), using visualizations and simulations.
The project later inspired me to create Pelagica, a more interactive size-depth visualizer, based on some of the datasets I used here.
Scatter plot of body length vs. minimum recorded depth for ~20,000 marine species, based on data from SealifeBase [10], FishBase [11], and taxonomic information from WoRMS [9]. The data are limited to species where minimum and maximum depths differ by less than 1,000 m. Colours indicate taxonomic orders; only those with ≥5 entries are shown. The line at a depth of 200m indicates what is generally considered the point of transition to the deep sea.
1 Introduction
Deep-sea gigantism (DSG) describes the apparent increase in body size with depth in certain marine invertebrates such as amphipods, isopods, mysids, and copepods [1], with Bathynomus giganteus (up to 50 cm [2]) being a well-known example. Proposed drivers include pressure- and temperature-related metabolic changes, slower life histories, and selective advantages for mobility and foraging in resource-scarce environments [1].
2 Motivation
DSG is often cited as a pattern, but it is rare [1] and the evidence inconsistent due to sparse and incomplete data. Only around 240,000 marine species have been described out of an estimated 2.2 million [3], and most available data are limited to single specimens (e.g. [4]), often missing key variables like temperature, age, or sex. Body size can vary widely even within a species due to genetics and environment, making broad comparisons difficult. The plot above illustrates this data granularity issue: even with 20,000 species, no consistent size–depth trend emerges even for those species hypothesized to be affected by DSG. Note also that the existant datasets required using length as a proxy for body size. These limitations suggest that more structured, model-based approaches are needed to evaluate when and how DSG-like patterns might arise.
3 Methodology
(coming soon)4 Results
(coming soon)5 Discussion
(coming soon)
References
[1] Nybakken, J W. Marine Biology: An Ecological Approach. Addison-Wesley Educational Publishers Inc. 1997
[2] McClain et alii. Sizing ocean giants: pat- terns of intraspecific size variation in marine megafauna. PeerJ. 3: e715. doi:10.7717/peerj.715. 2015
[3] Ocean Census. oceancensus.org/mission. 2024
[4] Ocean Biodiversity Information Sytem. obis.org. 2024
[5] Image citation: Bathynomus giganteus. NOAA (retrieved from Wikimedia). October 2002
[6] Image citation: Armadillidium vulgare. Xeroporcellio (retrieved from Wikipedia). March 2024
