Tales from Aquavet: Invertebrates


An unidentified crustacean viewed under a light microscope

This summer I had the amazing opportunity of being a part of the AQUAVET I program at Roger Williams university in Rhode Island. In those four weeks I got to see some breathtaking things ranging from porpoise necropsies to New England costal sunsets. I learned a lot about many aquatic creatures, their anatomy, ecology and clinical techniques used and I loved every moment of it. Although fish and aquatic mammals seem like they would have been the stars of the show, in my mind it was the many invertebrates we encountered that stimulated my interest the most. Like many others, I didn’t know much about invertebrates before coming to AQUAVET, nor did I think about the role they play in aquatic ecosystems.

An unidentified hermit crab

Interestingly enough, after the administrative lectures were finished, the first thing we started with was invertebrate biology. Starting with basic ecology and Identification of Bivalvia, we quickly moved into the anatomy and physiology, which in some ways is similar to that of vertebrates but also very very different (for some cool anatomy look up “crystalline style”). These lectures were led by our co-course director, parasitologist, bivalve enthusiast, and amateur (in my opinion professional) bartender Dr. Robert Maze, who then led a lab where we were able to dissect specimens to further understand the anatomy.  Learning all of this inspired me to think more about the role that invertebrates and invertebrate health play in both the ecosystem and in our daily lives through the food we consume. Often it is easy to forget that animals so different from us also get sick and this was a great reminder that as a veterinarian we are committed to improving the health and wellbeing of all animals. We continued through the first part of the week learning more about the many aquatic invertebrates from worms to cephalopods to starfish culminating in a day long lab where we were able to collect, observe, identify (and eventually release) many native aquatic invertebrates from the local beach during low tide. Although this marked the end of the invertebrates unit, we still discussed invertebrates many more times especially in lectures about food and food safety.

A purple sea urchin, Arbacia punctulate, found during the invertebrate collection lab

When one thinks seafood, obviously a nice salmon filet or a tuna steak comes to mind, but you also think about oysters, crabs, shrimp, lobster, squid, and maybe even sea urchins if you can stomach that. Many of these animals are commercially fished and farmed but rarely do we think about their health. Interspersed throughout the rest of AQUAVET we had lectures which discussed more applicable and clinical topics affecting invertebrates such as major diseases of shrimp and bivalve farms, husbandry of bivalves, food safety concerns regarding uncooked or incorrectly kept seafood. We also got to participate in labs where we learned about how to draw hemolymph on a suite of inverts as well as interpret hematology slides. One of the last encounters we had with invertebrates was on our field trip to the Long Island Aquarium where we had the opportunity to see an amazing coral reef tank and had a lecture on corals and the history of the aquarium, we even got to propagate our own corals!

When looking back at my time at AQUAVET, learning about invertebrates was probably one of the most exciting parts because there was so much new stuff to learn. I hope this article has piqued your interest in invertebrate medicine and will make you want to learn more about their biology and health.


CLICK HERE to learn more about the AQUAVET® program.  CLICK HERE to see our other posts about AQUAVET®.


Kwamina Otseidu, class of 2021, graduated from Michigan State University with a B.S. in Environmental Biology/Zoology. He has an interest in Aquatic Animal Medicine and Pathology.

Hook, Line, and Suture: Fish Surgery 101

Chris Payne (’21) performing his first fish surgery during AQUAVET® I.

Usually, when vet students scrub in to perform surgery for the first time, it’s to spay or neuter a dog or cat. For me, that wasn’t the case. My first scrub in, and my first (group) surgery, was for a splenectomy in a fish. Yes, that’s right—a fish. Fish surgery is just one of the amazing opportunities provided by AQUAVET® I, a four-week summer program that teaches students about aquatic medicine, a topic that’s not part of the core veterinary curriculum. As someone who had absolutely zero surgery experience, and even less experience working with fish, I was a mess of nerves and excitement. Thankfully, the faculty were there with us every step of the way, making sure that our surgeries went smoothly.

The surgery started as all surgery starts, with induction. Inducing a fish is actually pretty simple: after determining what concentration of anesthetic you needed to induce, you add a one-to-one mixture of MS-222 (the only anesthetic currently approved for use in finfish) and sodium bicarbonate to an induction tank. Once dissolved, you add the fish and wait for the anesthetic to kick in. Like most animals, fish will begin to slow down their movements and breathing once they’ve been induced. To monitor a fish’s breathing, we look at its opercular movements. The operculum is the flap of skin over the gills, and its movement indicates the fish’s respiratory rate. Once the fish has started operculating very slowly and doesn’t respond to being touched or grabbed, it’s safe to transfer them to the surgery set up.

Viscera of a bony fish.  The ovaries would be located in approximately the same location as the testes in this diagram.  Image source: Gratzek, J. B. (1992). Fish anatomy, physiology, and nutrition. Morris Plains, N.J.: Tetra Press.

Our surgery set up was pretty simple: a spay pack, a plastic trough, two large plastic tubs, and a lot of plastic tubing. The fish that I was about to operate on was placed in the trough, where the plastic tubing was inserted into her mouth to keep water flowing over her gills (so she could still get oxygen). That tubing split off via two valves, and each of the two branches lead to one of the tubs. One tub was full of regular seawater, and the other was full of MS-222 solution at a maintenance concentration. This allowed my surgical team to switch between regular seawater and anesthetic, to keep our fish at the desired level of anesthesia. We also injected our patient pre-operatively with ketoprofen, an NSAID, for pain management.

Once our patient was knocked out, it was time to start surgery. The surgery was the same as any other organ removal surgery; once we opened our patient, we located the spleen, isolated it from the surrounding connective tissue and arteries, and then ligated it and removed it. We also performed an ovariectomy (removing the ovaries), which was a little harder than removing the spleen. The ovaries of a fish straddle the colon, so we had to thread one of the ovaries under the colon, so that the two ovaries were on the same side. Once there, we simply ligated the ovarian blood vessels, and then removed the ovaries!

Recovering our fish from anesthesia involved completely shutting off the flow of water from the anesthetic tank, and placing her in clean seawater. We expedited the fish’s recovery by (gently!) moving her forward, to increase the flow of water over the gills. At some point the fish had righted herself and maintained that position, which was a good sign that she had recovered!


CLICK HERE to learn more about the AQUAVET® program.  CLICK HERE to see our other posts about AQUAVET®.


Chris Payne, class of 2021, is a current student at Cornell University’s College of Veterinary Medicine. Despite growing up mostly in Oklahoma, Chris has always had a deep interest in everything related to the ocean, and hopes to work as an aquarium veterinarian in the future.

AQUAVET: A Quest in Understanding Aquatics in a Very Efficient Timeframe

AQUAVET students in Woods Hole, MA – June 2017.

First, let’s clear the air. Err, water. Yes, you can do surgery on a fish.  No, fish surgery doesn’t happen underwater.

I’m Jason Sifkarovski, a second year vet student interested in zoo and conservation medicine.  Naturally, these encompass aquatic medicine, but it can be tough to find such opportunities within a traditional curriculum.  This past summer, I joined fellow Cornellians, veterinary students, and veterinarians from around the world in AQUAVET®, a month-long course in aquatic animal medicine.

AQUAVET® was first taught in Woods Hole, MA over 40 years ago as a joint venture between Cornell and the University of Pennsylvania.  Today, the course’s faculty boasts an impressive list of dozens of alumni and other professionals who all migrate to its current home at Roger Williams University in Bristol, RI.  I expected my fair share of fish facts, but I was blown away by the breadth of the curriculum.  Invertebrates, birds, fish, reptiles, and marine mammals were all covered; we dove into natural history, anatomy, and physiology before flowing into species-specific disease, diagnostics, and treatment.

Our first lab had us collecting invertebrates in the intertidal zone for viewing under dissecting microscopes. A super up-close sea star is a sight to see!  Oysters, clams, and crabs kicked off the first of our dissections, followed by fish.  Starting the course off with invertebrates and shellfish made me quickly realize aquatic medicine extends far beyond aquariums and conservation. Invertebrates in veterinary medicine may sound fishy, but become much more relevant when considering the billions of dollars wrapped up in shrimp farming alone. Aquaculture’s share in global food production is rapidly rising, and veterinarians will become increasingly important to ensure food safety and sustainability, just as they are for more traditional food production.

For each species group we studied, lectures were followed by diverse selections of specimens for necropsy and histopathology.  Lectures and labs were led by veterinarians in government, aquariums, research and industry, and even private practice.  Each tied their experiences into the topics they discussed, contextualizing the relevance of each species and the current state of medicine.  For example, we realized there were more species of fish in our lab than there are legal antibiotics for fish in the United States.  That’s a sobering thought for a medical professional, but it did hammer home the idea that much work needs to be done in this relatively young field.  By the end of the course, we had necropsied sharks, skates, turtles, crocodiles, ducks, gulls, and more.  That’s a lot to take in for even the most fervent zoologist, but every day felt fresh and reinvigorating.

Beluga whale at Mystic Aquarium awaiting further instruction (or fish).

Despite all the time spent in the classroom, field trips got us outside of our bowls as well.  We explored different types of aquaculture production systems with tours of fish hatcheries, and traveled to the Woods Hole Oceanographic Institute to learn about aquatics research, and to conduct necropsies of dolphins and seals – a messy endeavor, but certainly the one I had anticipated the most.  My favorite trips, however, were the aquarium visits.  We performed penguin physical exams at the Long Island Aquarium, a private institution home to one of the world’s biggest reef tanks.  We toured the New England Aquarium, home of the aptly-named Giant Ocean Tank and several floors of exhibits.  Veterinarians at Mystic aquarium brought us along for beluga whale feedings (they’re trained to take a gastric tube for stomach content sampling!) and their reality TV-themed sea lion show, which puts a twist on education and helps visitors connect with, and retain, important messages about conservation.  Given how zoos and aquariums have come under fire for captive marine mammal programs, I was particularly interested in how these institutions conveyed their conservation and educational messages to the public.  These institutions serve to not only provide a safe and healthy environment for their own animals, but also conduct research and lead massive, publicized conservation efforts to provide for those in the wild.  By keeping the public engaged through fun, yet educational, demonstrations like sea lion shows, they slowly but surely help the public feel involved in conservation themselves.

Performing a splenectomy on trout.

The highlight of the course was our surgery lab.  We practiced suturing and dosing anesthesia in the days leading up to the main event: splenectomies and ovariectomies on trout. Since fish use their gills for gas exchange, powdered anesthesia is typically administered to water which may then be washed over the gills and recirculated using pumps; this means the entire fish can be held out of water for the duration of surgery.  We worked in teams to calculate doses, administer anesthesia and analgesia, excise organs, and suture the incision closed.  I quickly learned that fish scales provide a whole new challenge for blood draws, injections, and suturing.

When I arrived at RWU, I anticipated a course focused mostly on captive animal medicine and husbandry with some emphasis on conservation. Four weeks later, however, we had also covered aquaculture, public health, toxicology, private fish practice and trade, and countless other topics.  Of course, each of these topics ties in to conservation, and I never anticipated how many extra tools I would come away with.  In all its breadth, aquatic medicine suddenly felt so much more expansive, yet being taught by so many connected people made it feel accessible and intimate. I befriended terrific students who made me genuinely excited to start each day, and I can’t wait to see how many of these new friends will be teaching the course down the road.  AQUAVET® provided even more than I wanted, both personally and professionally, and it can surely do the same for anyone else willing to get their feet wet.

The sea lion star of the show at Mystic Aquarium in Connecticut.


Jason is a second-year veterinary student at the Cornell University College of Veterinary Medicine. He previously graduated with a Master’s Degree in Microbiology & Immunology from the University of Rochester School of Medicine and Dentistry.  Jason is pursuing a career in clinical zoo and conservation medicine while also maintaining interest in government and policy.