//
you're reading...

Biology

Cuttlefish “freeze-out” their predators

Article:

Bedore, C. N., Kajiura, S. M., & Johnsen, S. (2015, December). Freezing behaviour facilitates bioelectric crypsis in cuttlefish faced with predation risk. In Proc. R. Soc. B (Vol. 282, No. 1820, p. 20151886). The Royal Society. DOI: 10.1098/rspb.2015.1886

Introduction:

Regardless of size or shape, all organisms in the ocean face the same three basic challenges: find a mate, find food and avoid being eaten in the process. Avoiding predation can be tricky because the ocean is full of many large predators and suitable hiding places are limited. However, over time organisms have evolved different ways to avoid predation. In the case of cephalopods, such as squid, cuttlefish and octopus, this evolution has resulted in some extraordinary camouflage techniques. Cephalopods are able to match the color and texture of their background to render themselves nearly invisible to potential predators (for more on camouflage, check out this post!).

Though effective, cephalopod camouflage does not offer a 100% success rate. For instance, sharks are very successful in hunting cephalopods and use passive electrolocation to find visually hidden prey. Sharks have sensors that can pick up electric signals, which are produced by every animal in the ocean. For fishes, these signals are created at the gills as a result of ion exchange with the seawater. More ventilation at the gills means more electrical signals are produced. This begs the question: how do cephalopods have a chance at survival when even basic ventilation works against them? Well, the evolutionary “cat-and-mouse” game between predator and prey has become even more interesting. It appears one species of cuttlefish has evolved to reduce its electrical output via a behavioral freeze response. A group of researchers set out to test the effectiveness of this freeze technique in cuttlefish and how it may lower predation from sharks.

Cuttlefish methods

Figure 1: Illustration depicting the recording of electrical signals from enclosed cuttlefish. Electrodes were placed near cuttlefish openings and a looming virtual predator was presented on an iPad.

Methods:

Cuttlefish (Sepia officinalis) and two types of sharks (bonnethead and blacktip) were used in the experiments. The first objective was to record baseline electrical voltage and frequency measurements from cuttlefish ventilating by themselves in the tank. They placed electrodes in the tank and measured electrical output associated with each body cavity opening (siphon, funnel and mantle cavity) of the cuttlefish (Fig. 1). They also measured voltage and frequency when the openings were blocked by the arms, which helped determine the insulating effects of the skin.

Using these electrodes, the scientists tested the electrical response to a looming predator. No cuttlefish were harmed in this study – instead cuttlefish were exposed to videos of sharks on a nearby iPad (Fig. 1). The response of cuttlefish to this virtual predator was scored as no response, freeze, or jet (escape) depending on the electrical output. Live sharks were exposed to either a freeze, resting or jet-simulating current typically produced by cuttlefish. The sharks’ behavior towards the different electrical currents was observed.

Cuttlefish recordings

Figure 2: Bioelectric potential (voltage) recordings at the funnel (green), siphon (blue) and mantle (red) openings. Voltage was reduced by 50% when openings were closed and greatly increased when jetting occurred (black column).

Results:

When cuttlefish were by themselves in the tank they produced electrical voltages ranging from 10-30 µV at the siphon, funnel and mantle openings. These voltages were lowered when openings were closed and much higher when cuttlefish jetted away (Fig. 2). Cuttlefish drastically altered their behavior in the presence of virtual shark predators. Instead of trying to flee from the predator, cuttlefish froze until the stimulus was taken away. This freeze response significantly lowered both electrical voltage and frequency. In addition, “frozen” cuttlefish decreased their mantle height and slowed body movements during ventilation. So, when threatened by shark predators (albeit virtual), cuttlefish chose to freeze rather than escape.

Cuttlefish shark recordings

Figure 3: Shark response to cuttlefish-simulating electric fields. Freeze, rest and jet-simulating electric signals shown. Response is shown as percentage of bonnethead (grey columns) and blacktip sharks (black columns).

What happens when we look at the freeze response from the viewpoint of the sharks? Both shark species bit at freeze-simulating electrodes only half as often as they bit rest-simulating electrodes. When sharks were exposed to jet-simulating electrodes, the bite response was even more pronounced (Fig. 3). Sharks responded more aggressively and attacked electrodes more often when they were emitting a resting or jetting-simulating current. It seems a freeze response offers cuttlefish the most refuge from shark predators.

Conclusion and Significance: 

In the face of a looming shark predator, cuttlefish chose to freeze instead of flee. This freeze response lowers the electrical field of the cuttlefish, limiting the shark’s ability to use its sensory detection. In the ocean, fleeing away from a nearby shark may draw unwanted attention to the cuttlefish. Though cephalopods often perform inking when they dart away, many shark species are chemically attracted to ink products.

Elasmobranchs, such as sharks, place substantial predation pressure on cephalopods, thus electrical freezing may provide vital protection from nearby predators. This case is just one example of an evolutionary “arms race” between predator (shark) and prey (cuttlefish) in the ocean. Avoidance techniques such as the freeze response in cuttlefish help provide structure and stability to marine food webs. Further research on these predator-prey interactions is necessary to understand life in the ocean.

 

 

Discussion

One Response to “Cuttlefish “freeze-out” their predators”

  1. need to keep cuttle fish frozen for a long time….how???????yahyas28@gmail.com

    Posted by Ahmed AlgharasI | December 6, 2016, 4:33 am

Leave a Comment on Ahmed AlgharasI Click here to cancel reply

Instagram

  • by oceanbites 2 hours 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 weeks 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 2 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 3 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 3 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 3 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 4 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 4 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 4 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 5 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 5 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 5 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 5 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 6 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 7 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 7 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 7 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 8 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 9 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 9 months 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