//
you're reading...

Biology

Fatter Whales Float Better

 

 

Nousek-McGregor, A. E., A.C. Miller, M.J. Moore, D.P. Nowacek, 2013. Effects of Body Condition on Buoyancy in Endangered North Atlantic Right Whales, Physiology and Biochemical Zoology 87(1):160-171.  Doi: 10.1086/671811

Diagram of a North Atlantic right whale. (Col, Jeananda. Enchanted Learning. http://www.EnchantedLearning.com 1996)

Diagram of a North Atlantic right whale. (Col, Jeananda. Enchanted Learning. http://www.EnchantedLearning.com 1996)

North Atlantic right whales Eubalaena glacialis weigh an average of 70 tons as adults.  They can grow up to 18 meters and may live for more than 100 years.  They are dark in color, have no dorsal fin, and have callosities on the head region (Figure 1).  Right whales are baleen whales meaning they filter food, including zooplankton and copepods, from the water using their baleen as they swim.  An important feature for North Atlantic right whales, as well as other marine mammals, is their blubber which can range from 3.0 inches as juveniles to 8.5 inches when fully matured.    Blubber is important for marine mammals because it stores energy, is a thermal insulator, allows for easier gliding through the water, and has low density which makes it positively buoyant (it floats).  It is important for whales to be positivity buoyant because their survival requires them to dive deep in order to eat and their buoyancy aids returning to the surface to breathe.

Feeding grounds: North Atlantic right whales migrate seasonally along the eastern coast of the United States. Credit: Adapted from E. Paul Oberlander, Woods Hole Oceanographic Institution Graphics; Data from North Atlantic Right Whale Consortium

Feeding grounds: North Atlantic right whales migrate seasonally along the eastern coast of the United States. Credit: Adapted from E. Paul Oberlander, Woods Hole Oceanographic Institution Graphics; Data from North Atlantic Right Whale Consortium

Blubber is a direct factor of nutrition; when the metabolic demand is greater than what the available food supply can supply blubber is utilized for stored energy. This is often during molting, migration, pregnancy, and lactation.  North Atlantic right whales feed and build up their blubber stores in colder northern waters off the eastern coast of North America during the spring and summer.  Pregnant females then migrate 1,500 km south to calving grounds off of southeastern United States in the fall, give birth in the winter, feed the calves during the spring, and then return to the Northern waters before they feed again (Figure 2).   The reduction in blubber during these months can make the animal colder and less buoyant, requiring it to use more energy to maintain a stable temperature and to propel itself towards the surface from a deep dive. The study by Nousek-McGregor et al., (2013) addresses how differences in blubber affect buoyancy by monitoring the ascending and descending dives of right whales using non-invasive monitors.

Methods:

The North Atlantic right whales observed for the study vary in age, sex, and reproductive states (Table 1).   Identification of individuals was by a long term photo catalog while blubber thickness was measured with ultrasound devices and diving behavior was monitored with noninvasive archival tags.    The research goal was to use the information to investigate the relationship between body condition and buoyancy and to investigate how any changes were compensated in the dive behavior.

Individual whale information

Individual whale information

Whales were tagged in the Bay of Fundy during August 2000 – 2002, and 2005.  Archival tags attach via suction cup about mid-way on the whales body. When they are full of information they detach from the whales, float to the surface, a send a signal to be retrieved. The tags collected data on the whale’s motion around three axes to measure movements during descent and ascent like gliding, active swimming, or stroking.

Results/Discussion:

As expected, the researchers found that whales with thicker blubber spent more time gliding during ascent than whales with thinner blubber, or in other words, the fatter whales float to the surface faster.   For the descent it was observed that the thicker blubber whales glide less than thinner blubber whales as expected because whales with more blubber have to fight a greater buoyant force.     The questions then become: is the cost of energy per dive greater for a thick blubber whale or a thin blubber whale?  And is the cost compensated by altering dive mechanics?

It was found that whales with thicker blubber have a greater difference between the ascent and descent dive angles compared to the thinner blubber whales.  It is speculated that the dive angle may influence the hydrodynamics making it easier to glide through the water, however more information is needed to claim definitive statements.

Importance:

North Atlantic right whales are important to study because the population is on the Endangered Species list.   It is thought that a limitation to population recovery is related to a lack of nutrition that hinders efficient reproduction.   In this study, for example, the lack of nutrition linked to changes in blubber content was particularly trying on lactating females.    As the availability of food changes with changing climate and environmental conditions it could increase the threat to the right whale population.

Discussion

One Response to “Fatter Whales Float Better”

  1. Best title ever

    Posted by Carrie McDonough | March 3, 2014, 12:06 pm

Post a Comment

Instagram

  • 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