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Biology

Oceanbites at the Society for Integrative and Comparative Biology: Part II

SICB_LogoWith over 2,000 attendees and more than 1,800 scientists presenting their research- this year’s meeting of the Society of Integrative and Comparative Biology in Portland, OR was the largest meeting of the society yet. With so many fantastic talks, it was impossible to see them all. Luckily, there were two oceanbites authors present to report back. On Wednesday, Dina shared her favorite talks and gave a great introduction to the meeting. Today, I will share more of the exciting research we saw in Portland by reviewing my favorite ocean-themed talks of the conference.

Life in Extreme Environments

Figure 1: Oxygen Minimum Zones are places in the ocean where oxygen levels (shown by the red line) are much lower than in other areas within the ocean. Image source:  msnucleus.org

Figure 1: Oxygen Minimum Zones are places in the ocean where oxygen levels (shown by the red line) are much lower than in other areas within the ocean. Image source: msnucleus.org

There was a day-long symposium on the biology of organisms living in extreme environments. My favorite from the session: “Physiological strategies of vertical migrating organisms in pronounced oxygen minimum zones” by Dr. Brad Seibel. Climate change is associated with increases in oxygen minimum zones, or OMZs (OMZs are regions in the ocean with substantially less oxygen; Figure 1). Dr. Seibel’s research addresses how animals may respond to these increasing OMZs by studying animal physiology. His talk focused on the jumbo squid (Dosidicus gigas ), which undergoes daily migrations through these OMZs. At night, these squids can be found in shallow water, actively hunting. But during the day, the squids migrate to deeper water (into the OMZs) and are much more lethargic. Dr. Seibel’s research found that while in the OMZ, the squids switch from aerobic metabolic pathways (normal metabolism where your body uses oxygen as fuel) to anaerobic metabolism (where oxygen is not used to fuel metabolic pathways). This switch induces a metabolic suppression, in essence slowing everything down and accounting for the sluggish behavior typical at depth.

What is interesting, is that when Dr. Seibel studied this squid and other closely related species in several locations (including the Sea of Cortez, off the coast of California, and the Red Sea), he found that the squids appear to preferentially migrate into OMZs instead of staying in water with enough oxygen to constantly fuel normal, aerobic metabolism. It seems that these squids are seeking out lower oxygen regions to induce a metabolic suppression; however, it is still unknown why or how increasing sizes of OMZs will affect these species.

Opsins are everywhere!

Figure 2: Photoreceptors in the horseshoe crab (left) are found in several places on the shell and along the tail. In the fan worm (right), photoreceptors are also found on the gills (the purple structure which sticks into the environment). Image credit for horseshoe crab: horseshoecrab.org

Figure 2: Photoreceptors in the horseshoe crab (left) are found in several places on the shell and along the tail. In the fan worm (right), photoreceptors are also found on the gills (the purple structure which sticks into the environment). Image credit for horseshoe crab: horseshoecrab.org

There was another day-long symposium on extraocular opsins. Opsins are the light-sensitive proteins found in the eye and are used for vision. Recently, scientists have been finding opsins in all sorts of strange places like the nervous system, fins, muscles, skin, and even in the mechanosensory, flow-detecting organs in fishes. Nansi Colley gave a talk on “Photoreception in phytoplankton”, a topic we have covered on oceanbites before, but found so incredible that I believe it is worth mentioning again. An odd group of dinoflagellates (called Warnowiids) have an eye-like structure that may be capable of forming images. Let me reiterate how cool this is: a single cellular organism has an ‘eye’!

Other notable talks in this session included Barbara Batelle’s overview on the photoreceptors found on the tail and in several places on the carapace of the horseshoe crab and Mike Bok’s research on the photoreceptors found on the gills of the fan worm (Figure 2). How these photoreceptors and opsins are used by the animals in not fully understood but it looks like we will see a lot of exciting research in this field in the future.

The Cock-eyed Squid: “The perks of being cock-eyed: orientation and visual characteristics of histloteuthid squids”

Figure 3: The cock –eyed squid (Histioteuthis heteropsis) has 2 different sized eyes pointing in opposite directions. Image credit: MBARI; modified by author

Figure 3: The cock –eyed squid (Histioteuthis heteropsis) has 2 different sized eyes pointing in opposite directions. Image credit: MBARI; modified by author

Kate Thomas from Duke University presented her research on this odd looking, deep-sea squid (Figure 3). Cock-eyed squids (Histioteuthis heteropsis) have one normal sized eye, and one eye that is much larger-and both eyes point in different directions! There have been several hypotheses on how each eye functions but in order to better understand this strange animal, Thomas analyzed videos of the squid taken in its natural environment by the Monterey Bay Aquarium Research Institute’s remotely operated vehicles. She found that living squids swim so that the large eye faces up (towards the ocean’s surface) and the small eye is directed downward. The large eye also has a yellow pigment which may allow the squid to break up the silhouettes of bioluminescent organisms which are camouflaged in the twilight zone via counter illumination (counter illumination is when an animal matches the light intensity of the environment with its light organs, or photophores, thereby creating camouflage). These behavioral insights can help scientists determine the function of the dimorphic eyes. For more information on this fascinating animal watch this video from the Monterey Bay Aquarium’s Research Institute.

The Invisible Shrimp: “The limits of an invisibility cloak: transparent shrimp become opaque after multiple tail-flipping escapes”

Figure 4: An anemone shrimp appears invisible except for bright spots of purple, red, and white color. Image credit: divegallery.com

Figure 4: An anemone shrimp appears invisible except for bright spots of purple, red, and white color. Image credit: divegallery.com

Laura Bagge from Duke University has been studying how some animals can appear invisible. This trick is more than just making everything transparent because these animals still have all the normal body parts that non-transparent animals do (like muscles, blood vessels, and internal organs). One cannot simply make an organ see through! So what’s the secret? Well, it is a major illusion, in which the animal uses light refraction to appear transparent without actually being see-through! These animals have to minimize the amount of light that is scattered by their bodies- and some animals, like certain shrimps (Figure 4), are quite good at this optical illusion. But Bagge noticed that sometimes these shrimp are not so great at staying invisible- like when they swim away from predators they tend to turn an opaque white color. Bagge has found that exercise, which increases the flow of the hemolymph (crustacean blood), actually increases the amount of light scattered by the shrimp’s body. This disrupts the shrimp’s well-designed optical illusion and causing it to become visible.  Maybe working out isn’t always the healthiest option….

 

As expected, this 2016 meeting of the Society of Comparative and Integrative Biology was filled with fantastic talks, exciting science, and excellent networking opportunities. If you like hearing about the science being presented at conferences like this, keep your eyes open for more conference summaries from our oceanbites authors!

Ashley Marranzino
I recently graduated with my MS from the University of Rhode Island. I specialize in studying fish biology/ecology, and deep-sea biology but love all things to do with marine biology.

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