Coral Reef Adventure

I was excited to develop and teach a weeklong Coral Reef Adventure course for Nueva Summer this year! During the remote class, students were immersed in the most biodiverse marine ecosystem on Earth— the coral reef. Through activities like engineering a coral polyp out of household items and virtually diving the extraordinary reefs of Palau, students explored the fundamentals of coral reef ecology. 

Diving in Palau. Photo by R. Ritson-Williams

Students were introduced to a dazzling array of creatures through my own underwater photography taken while SCUBA diving in places like Hawaii, Belize, and Bali. We also investigated current threats to coral reef diversity and the cutting-edge science of coral reef conservation. Here, I will share a few highlights of the course that were things I tried for the first time and recommend. Let's dive in...

Coral Polyp-Palooza

Reef-building corals form the structure for the entire ecosystem, and they are actually colonies made up of hundreds or thousands of little coral polyps. A coral polyp is a single coral animal. One of our very first lessons involved coral polyp anatomy and physiology. Though it can vary across species, the basic body form of a mature polyp is a sac-like gastrovascular cavity inside a calcium-carbonate skeleton. There's a central mouth ringed by feeding tentacles armed with stinging cells called nematocysts. 

A coral polyp.

Tiny zooxanthellae algae live within the tissues of the polyp. Corals provide the  zooxanthellae with a protected home and the coral's waste gives energy to the zooxanthellae. Through the process of photosynthesis, the zooxanthellae produce food for the coral. Since they both benefit from each other, the symbiotic relationship is referred to as mutualism.

After that brief introduction, there was a coral polyp design challenge. In the allotted time, students brainstormed, gathered materials, and constructed a creative coral polyp model. I encouraged students to make ephemeral models out of any household or natural materials (leaves, clay, food, beads, etc). To the right is a slide show of some of the homemade coral polyps!

3D Corals & Coral Bleaching

While our polyps were delightful, it's also an option to 3D print durable physical models of polyps or entire colonies. 3D models of actual coral specimens can be made using a technique called photogrammetry to “capture” corals in three dimensions. In the process, multiple 2D photographs of a coral taken from different angles are combined into one 3D digital model using custom computer software. Models can be created through photogrammetry of both living corals underwater and preserved specimens in a museum. These types of models can be made for scientific study, museum exhibits, education, aquariums, or just for fun! Non-profit organization called The Hydrous, committed to connecting people to the ocean through technology, has a diverse gallery of digital coral models (see them on SketchFab). Once you have a digital model of a coral, it can be easily 3D printed.

This model of a Pocillopora meandrina coral was 3D printed in the Nueva School's I-Lab with open access plans from The Hydrous you can find here. I was happy with the model, but I really wanted to experiment with a color change effect! So, next, I painted the model with a mix of plain acrylic base and a thermochromic powder that changes color with a temperature increase. I recommend printing the coral in white filament and then choosing a powder that starts as a bright color and turns to clear. The paint base and powder can be found at craft stores or sourced online.

A 3D printed coral colony.

Painting the coral model.

Watching paint dry.

Once the coral model's paint was completely dry, I was ready to test it. I placed the model in warm water to simulate coral bleaching - the phenomenon that is causing the rapid decline of coral reefs. In an actual coral, as water temperature increases, zooxanthellae leave the coral and it turns white (or appears to “bleach”). It's a total breakdown of the symbiotic relationship between the coral and its zooxanthellae. Students were amazed by the visual transformation— see it yourself in the short video below. 

This demonstration could be replicated with your own 3D printed coral models of various species. The models could also be used in the classroom as the basis for student investigations or for a high-impact demo in a STEM fair or other science outreach event.

All actual corals have bleaching thresholds, the temperature at which they will bleach, and this varies by species, shape, location, and a number of other factors. Sometimes, if conditions improve, zooxanthellae will repopulate and the coral will ultimately survive. Most often, though, a bleached coral will die. Thus, coral bleaching events due to climate change are a major threat to coral reef ecosystems worldwide. 

Virtual Dive

Our course culminated with a virtual reality (VR) dive through the spectacular reefs of Palau! All week in our Zooms, students had practiced the SCUBA diving hand signals to communicate their status (ok? distressed?) and to indicate the presence of reef creatures like octopus, sharks, and sea turtles. On dive day, students donned VR viewers and got to submerge into an underwater world. During the dive, students felt like they were really underwater and could look in all directions to explore their surroundings - they even put the hand signals to use!

Virtual field trip to Palau's reefs courtesy of The Hydrous!

I'm grateful that my friend Dr. Erika Woolsey, The Hydrous CEO and National Geographic Explorer, could arrange for ambassadors Andrea and Will to help us out. The dive itself is 360-degree VR movie titled The Hydrous Presents: Immerse. It beautifully recreates what it’s like to SCUBA dive, whether you're watching a huge manta ray glide overhead or looking down at the intricate and colorful reef below. The movie takes you on an underwater tour led by Dr. Woolsey and narrated by other marine scientists and young ocean advocates. Get your own preferred VR viewer- like this inexpensive Google Cardboard- and check out the film on YouTube! 

Additional Resources

Do you want to go deeper? To continue your own coral reef adventure, here is a curated list of some resources for learners of all ages:

• The Hydrous - read more about their mission, download your own 3D coral models, find educational resources, and get instructions for viewing The Hydrous Presents: Immerse VR movie
• Lost Cities - view interactive documentary by CaravanLab and Ruth Gates about coral reef science and conservation (self-paced).
• Expedition Reef - watch California Academy of Sciences animated planetarium show about coral reef ecology (25 mins).
• Chasing Coral - watch full-length Netflix documentary by Jeff Orlowski addressing threats to coral reefs (1 hr. 28 mins).
• Coral Reef Ecology - take a free mini-course by the Living Oceans Foundation (self-paced). 

And for teachers:

• Coral Reef educational materials - National Geographic Education
• Coral Reef educational materials  - NOAA's Coral Reef Conservation Program
• Investigating Coral Bleaching Using Data in the Classroomnoaa.maps.arcgis.com/apps/MapSeries/index.html?appid=bee500fe72174e49aa577205151a3ca0 - NOAA Data in the Classroom
  
• Expedition Reef for Educators - California Academy of Sciences