I recently had the opportunity to take a course on Marine invertebrate Zoology at Friday Harbor Laboratories (FHL). This is the third course that I have taken at FHL. These classes are world-renowned due to faculty who are pioneers in their fields, along with the incredible biodiversity of the Salish Sea, which is easily accessible from the labs. I have been highly interested in marine invertebrates for as long as I can remember, and my passion for this field has only grown after completing this course.
This program introduced students to the diversity of invertebrate life that exists on our planet. I was surprised to learn that 97% of described animal species are invertebrates, and there are over 30 phyla of invertebrates documented (Center for Biological Diversity). Our class learned about these phyla one by one, and we were able to observe approximately 24 of them from samples we collected during our field trips. There are not many places in the world where this many invertebrate phyla can be collected, which makes Friday Harbor the perfect location for this course.
Zoologists are experts in categorizing and describing animals, and they can use various techniques to accomplish this. Many organisms are distinguishable by observation alone, but often molecular techniques are needed to distinguish cryptic species — species which are reproductively isolated but morphologically identical. In order to differentiate cryptic species, DNA samples must be collected and sequenced to find polymorphisms, which are differences in the genetic code in the same gene of two individuals. If there is a difference greater than 5% in an individual gene and there is also a significant difference in the genetic code of other genes, this can indicate that one species may actually be two. In this course, animals were collected, and their DNA was sequenced in order to identify new cryptic species.
This class taught me that there are many more species of animals in existence than there are currently described, and it is important for zoologists to find and document as many as possible so that we can have a record of the life that exists on our planet. Currently, our planet’s climate is changing at a rate faster than ever before, which makes it even more crucial to document as many species as possible as quickly as possible. If more species are described, there are more species to be studied in order to understand the full extent of the changes in animal diversity caused by climate change.
The Problem:
The earth is currently warming due to the release of greenhouse gases into the atmosphere from human activity. This is causing the ocean is experiencing significant changes in its chemistry, which affects many marine invertebrates (NOAA). One of these greenhouse gases is carbon dioxide (CO2). The increase in the release in CO2 has caused an increase in the oceanic uptake of CO2; when CO2 enters the ocean, it combines with water to form carbonic acid. The increase in the concentration of carbonic acid leads to a decrease in the pH of the ocean. The pH scale is logarithmic, and the pH of the ocean has already decreased by 0.1 units; this is equivalent to an ocean that is approximately 30% more acidic than it was before the industrial revolution. If this rate of ocean acidification continues, the ocean will become more acidic than it has been in over 20 million years by 2100 (NOAA). As carbonic acid is formed from CO2 and water, an H+ ion is released (Hardt). This ion will often bind with a carbonate molecule to form bicarbonate (HCO3- ). The decrease of carbonate in the seawater will cause it to be more difficult for many marine invertebrates to form calcium carbonate (CaCO3). Additionally, when there is a very low amount of carbonate in the water, calcium carbonate that is already formed will dissolve (Hardt).
Calcium carbonate is critical for the survival of many marine invertebrate phyla (NOAA). CaCO3 is used by invertebrates as a material to build bones and skeletons. Depending on the invertebrate, calcium carbonate can either be formed by the organism or used directly from the surrounding water (NOAA). Examples of invertebrates that rely on calcium carbonate to survive are bivalves such as oysters, clams, and scallops, echinoderms such as sea urchins and sea stars, corals, and many types of plankton (Hardt). Many of the invertebrates who are being impacted by ocean acidification are commonly used for food by humans, such as bivalves, or are food sources for other organisms, such as plankton or echinoderms (Hardt). Ocean acidification is impacting both the ability of humans to collect food sources from the sea as a source of protein and the ability for the marine food webs to continue to function (Hardt).
Additionally, there is more than one type of calcium carbonate, and the equilibrium between them is shifting, which is causing an alteration in the distribution of many marine invertebrate species (Hardt). The two most common forms of calcium carbonate are aragonite and calcite, which are structural isomers (BIOACID). These two compounds have different solubilities and have different regions where they reach peak abundance, which may be viewed on this map. Calcite is less soluble than aragonite, and aragonite is decreasing more quickly in the tropics, where it previously had a high abundance (Henderson). Many invertebrates in the tropics, such as corals, build their calcium carbonate skeletons from aragonite rather than calcite. Unfortunately, the high solubility of aragonite in water of higher temperature explains why corals have been experiencing such a massive decline (in addition to the expulsion of their symbiotic zooxanthellae as the water temperature rises) (Henderson). Interestingly, a recent paper has found that corals have begun to migrate away from the equator in order to reach cooler waters that have higher aragonite concentrations. Read more about this here.
Although some species are showing resilience to changes in climate, it is essential to prevent as much change to the ocean environment as possible. Marine invertebrates were the earliest forms of animal life to evolve on our planet, and they have evolved over the past few hundred million years to be perfectly adapted for life in the different niches of the ocean. Marine invertebrates can exist in niches as small as the spaces between sand grains, or they may be pelagic and have tentacles that extend over 37 meters in length (Kosner). The ocean is changing faster than many of these animals can adapt to keep up with these changes, and many species will likely face extinction as temperature and acidity increase while aragonite availability decreases (Henderson). With the possibility of such a significant loss of biodiversity on the horizon, it is crucial now more than ever before to document the diversity of species which may be lost before it is too late.
Conclusion: I believe in the current state of our planet, this is the most critical time for zoologists to document the diversity of marine species. We are quite possibly the last generation of people who can observe this level of diversity of marine life before it is destroyed due to human activity. Documenting as many species as possible will allow researchers to have a grasp on how our ecosystem is changing in each niche by collecting data on the that organisms that exist there. I find it frustrating that there is so much life that is at great risk of being lost, but seemingly so few people who seem to care enough to find ways to make a difference.
I remember in April of 2019 when the Notre Dame caught on fire, and millions of people were devastated to watch this ancient building turn to ash (Henley). This building was first completed in 856 A.D. and has been adored by millions of tourists each year afterward. Although this building was partially destroyed by a fire, there were millions of pictures taken of the structures that burnt down and a lot of information was known about the structures so that the building may be reconstructed as accurately as possible (Henley). I see many similarities between the work of historians, who collect information about buildings from the past, and the work of zoologists, who collect information about animals that may be used in the future. Zoologists are the historians of the natural world, documenting the breadth of life that exists on our planet at this moment in time. Unlike Notre Dame, marine invertebrates have existed for approximately 3.5 billion years, and also unlike the destruction of Notre Dame, their destruction is more gradual and does not catch as much attention. Lastly, these organisms have an essential role as the foundation of ocean life and are crucial for the function of marine ecosystems globally.
At the beginning of this course, I was not entirely sure what the role of a marine invertebrate zoologist was. I am grateful to have taken this course because it opened my eyes to a field of study that is crucial for understanding how our oceans function. I am determined to learn more in order to document the invertebrate diversity on our planet. Below are some photos that I took both in the lab and in the areas where specimens were collected. I highly enjoyed the beauty of each phyla that we encountered over the course of these 5 weeks, and I hope you do too.
*sources are cited at bottom after photo gallery
Invertebrate Photo Gallery
Sources:
BIOACID. (n.d.). Two forms of calcium carbonate: Calcite and aragonite. Retrieved July 24,\ 2019, from https://www.oceanacidification.de/calcite-aragonite/?lang=en Center for Biological Diversity. (n.d.). Retrieved July 24, 2019, from https://www.biologicaldiversity.org/species/invertebrates/ Hardt, M., & Safina, C. (2015, December 24). Covering Ocean Acidification: Chemistry and Considerations » Yale Climate Connections. Retrieved July 24, 2019, from https://www.yaleclimateconnections.org/2008/06/covering-ocean-acidification- chemistry-and-considerations/ Henderson, Caspar. "Paradise lost: as the oceans turn acid, coral reefs will vanish along with innumerable other sea creatures. Caspar Henderson reports on a disaster in the making." New Scientist, 5 Aug. 2006, p. 28+. Business Collection, http://link.galegroup.com/apps/doc/A149767370/ITBC?u=wash_main&sid=ITBC&xid=4e 387fcf. Accessed 24 July 2019. Henley, J. (2019, April 17). France announces contest to redesign Notre Dame spire. Retrieved July 24, 2019, from https://www.theguardian.com/global/2019/apr/17/france- announces-architecture-competition-rebuild-notre-dames-spire Kosner, A. W. (2012, July 10). Lion's Mane Jellyfish Image: This Is (Literally) How Things Blow Up On The Internet! Retrieved July 24, 2019, from https://www.forbes.com/sites/anthonykosner/2012/07/10/lions-mane-jellyfish-image-this-i s-literally-how-things-blow-up-on-the-internet/#61513a0c6a32 NOAA. (n.d.). What is Ocean Acidification? Retrieved from https://www.pmel.noaa.gov/co2/story/What is Ocean Acidification?