Did you know that we can learn about the biology of animals through their feces?

Yes, their poop!

Here’s the scoop on studying poop at the New England Aquarium: Currently, scientists in the Anderson Cabot Center for Ocean Life are using fecal samples to study the endocrinology of the northern fur seals living at the New Balance Foundation Marine Mammal Center.

katie at work in lab
Anderson Cabot Center researcher Katherine Graham at work in the lab.
Endo-what?!

Endocrinology is the study of hormones. Hormones are tiny chemicals that circulate in the blood to signal all sorts of bodily processes, including growth, metabolism, reproduction, and many others. The hormones that we are studying in the fur seals are the same types of hormones found in our bodies (and in many other animals)!

fur seal on rock
A northern fur seal is perched on a rock in the marine mammal center.
So how do hormones end up in poop?

After the hormones have relayed their message, they are broken down by the body and ultimately get excreted in the feces.

Why use poop—couldn’t you measure them in blood?

We could measure hormones in blood, but we prefer feces because it can be collected without disrupting the seals’ day-to-day activities—like playtime. As opposed to taking a blood sample, we can just pick up the scats left behind. The trainers clear the exhibit every day, and the seals certainly don’t mind!

katie in lab
Pulling fecal samples from the freezer
How do you know whose poop is whose?

Each seal is fed a unique diet item (like lentils, sesame seeds, and barley) inside their fish. Since these food items don’t get fully digested, they appear in the scat and we can match the sample to the seal that made it.

The Marine Mammal Team collects the fecal samples and sends them to our research lab behind the scenes. We are lucky because the New England Aquarium is one of the few aquariums in the world that has a lab on-site to study hormones!

preparing dried poop sample
A dried fecal sample with dietary markers sifted out. This one had sesame seeds in it!
vials of feces samples ready for testing
Fecal samples that have been processed and are ready for testing.
How do you measure hormones?

In the lab, we perform several steps to extract the hormones from the feces and then measure the hormones using special tests called immunoassays. Currently, we are developing methods to measure hormones related to reproduction.

katie pipetting
Measuring fecal hormones using an immunoassay
assay plate
An immunoassay plate
Why study hormones?

By studying these hormones we can learn more about our seals at the Aquarium—for example which seals are going through puberty. Knowing more about the biology of the animals helps us provide them with the best possible care. We also hope to use these methods to study hormones in wild populations of northern fur seals, some of which are facing drastic declines.

Scientists in the Anderson Cabot Center for Ocean Life have performed similar studies for many years on other marine species—such as monitoring stress levels of endangered North Atlantic right whales in response to human impacts, such as noise and entanglement in fishing gear. These data are important to support conservation efforts for the species.

— Katherine Graham

Next time you are visiting the New Balance Foundation Marine Mammal Center see if you can spot any of the trainers collecting seal scat samples—for science! And keep an eye out for information about our research on fecal hormones.

signage in the MMC
Signage in the New Balance Foundation Marine Mammal Center