you're reading...


Fish and Fecal Figs: How does the size of one fish affect fig seed growth?

Reference: Santos, João, et al. “Differential ontogenetic effects of gut passage through fish on seed germination.” Acta Oecologica 108 (2020): 103628. https://doi.org/10.1016/j.actao.2020.103628

Most of us know that trees and other plants reproduce via seeds. However, it is sometimes not enough for a seed to simply exist in order to grow into an adult tree or plant. In many cases, the seed must be eaten by an animal, processed in the digestive tract, and then leave the animal as waste in order to grow, or germinate, into a plant. This digestion process coats the seeds in enzymes, acids, and other chemicals that tell the seeds it’s time to start growing. It can also mechanically process seeds (i.e. get rid of a hard outer coating) to make it easier for them to germinate once they reach soil. Birds often aid in germination, which is unsurprising since many of us have seen birds eating small seeds. But, did you know there are many cases where fishes can perform this process as well?

A Brycon species representative, Brycon hilarii. All Brycon species have a similar shape and coloration, though Brycon falcatus does not have the dark black horizontal stripe or red tinted fins, and instead has a black vertical stripe at the start of the tail. Image by David Morimoto via Wikimedia Commons.

One example is the fish Brycon falcatus, which frequently eats the seeds of the fig tree Ficus gomelleria. Brycon is mostly silver with a black vertical stripe on the tail, and can reach a little over a foot long. Fig seeds fall into the water, are eaten and digested by these fish, and then leave their bodies as waste. These processed seeds then germinate if the seeds make their way to adequate soil and are covered by it.

This fish-fig relationship is of particular interest because Brycon are currently threatened by habitat destruction. If these fish become extinct, this could have far reaching consequences to wider ecosystems, both aquatic and terrestrial. Researchers at the Federal University of Mato Grosso in Brazil wanted to examine this relationship between fish and fig more closely by asking a few questions: 1) are fig seeds that go through the digestive tract of Brycon actually more likely to germinate compared to seeds that have not? 2) does the size of the fish, and therefore the size of the digestive tract, affect the likelihood of germination? Quantifying this relationship allows for more targeted conservation efforts for these fish, and will allow this interesting relationship between plant and animal to continue into the future.

Fish fig feedings

A close up example of a whole fig fruit. Representative seeds of the fig are circled in black. This is a closely related species to Ficus gomelleria, Ficus carica. Image by Eric Hunt via Wikimedia Commons. Edited by Francesca Giammona.

In order to answer their questions, researchers collected wild Brycon fish from the Teles Pires River in Brazil. These fish were fed a meal with a fig seed, and then the waiting began for said seed to exit the fish. Fecal matter was vacuumed from the tank so seeds could be analyzed. Each fish underwent this process three times. Following the feeding trials, fish were sacrificed in order to measure the body length of the fish and the length of its intestines in order to accurately quantify size. Then, the seeds collected from the fish were planted, and growth (if any) was measured. This was compared to the growth of fig seeds that did not go through a fish’s intestines.

Did fecal figs flourish?

Overall, the seeds that passed through a fish’s intestines were over 10% more likely to germinate and begin growth into an adult fig tree. Not only were they more likely to germinate, but they tended to germinate a lot faster, about 50 days sooner on average. The average germination in this species will typically occur within 120 days, which may seem like a long time, but is perfectly normal for these figs!

Intestine length also affected the fig seeds. The longer the intestine, the less likely the seed was to germinate, with a rapid decrease in germination likelihood occurring once the intestines were longer than 10cm. The <10cm intestines also germinated seeds about 7 days quicker than all other intestine lengths.

The Teles Pires River in Brazil where the Brycon fish were taken for this study. Image by Gustavo Jordão via Wikimedia Commons.

What does this mean for figs?

The results of this study are a bit surprising given the life history of Brycon falcatus. When individuals are young (and have smaller intestines), they are typically carnivores, and only eat fruit such as fig if it’s readily available. When they are older, their diet shifts to solely fruit, and eating figs is much more commonplace. One would think that this relationship would then be that as the fish transition to a more fruit-heavy diet, they are better able to process the seeds and allow them to germinate.

Researchers suspect that as the fish become more accustomed to eating fruit and their digestive systems change, they process the fig seeds too much, causing the seeds to degrade or lose structures and compounds necessary to grow. Carnivorous young fish only eat figs on occasion, and so would not be able to process the seeds quite as thoroughly as their older counterparts.

Uncovering the details of this relationship between fish and fig is important for discussion of conserving Brazilian ecosystems, both in the water and on land, and will help to ensure these species can continue to thrive. This study also broadens our view of how plants and animals interact, providing an interesting example of how truly interconnected all life can be.


No comments yet.

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 6 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 9 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 9 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 11 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 12 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com