Long carapace spines help larval crabs swim

by Anna Smith and Amanda Kahn

We are used to seeing crabs scuttling across the seafloor or scrambling under rocks in the intertidal zone, but before they settle on the seabed they have larval stages that live in the water column as plankton.  Zoeae (pronounced zoe-EE-uh) and megalopae (MEG-uh-lope-ee) drift through the water, eating food and eventually metamorphosing into bottom-dwelling crabs.

Crab life cycle stages

Life cycle stages of a crab: an egg hatches into swimming zoea stages, then to a megalopa, then metamorphoses into a benthic juvenile and adult crab. Image credit: A Snail’s Odyssey

For her class project in Crustacean Biology (a summer course taught in 2012), Anna Smith worked with instructor Greg Jensen to study how swimming is accomplished by the zoeae of a porcelain crab, Petrolisthes cinctipes. Most crab larvae swim vertically in the water column and are fairly poor swimmers. These zoeae are swept along with the currents and are often taken out to sea with no hope of returning to the shore to settle. Check out the video below to see how zoeae of most crab species move in the water.

Most crab zoeae have sharply pointed spines projecting from their carapace, as pictured below. Previous studies have found these spines to be connected with predator avoidance by making the larvae harder to swallow. The zoeae of porcelain crabs, however, have unusually long spines sticking out the front and back of the carapace. They are also much stronger swimmers than zoeae of many crab species, enabling them to stay close to shore and avoid being swept away from settling grounds. These zoeae swim horizontally through the water column and exhibit much more directional control than most crab zoeae. Anna studied whether the elongated spines of porcelain crabs were connected to their unique swimming by studying their swimming ability with both spines intact, then removed the front, back, or all spines to see how their swimming changed.

Zoea of a porcelain crab

Zoea of a porcelain crab. Image credit: Greg Jensen 2015. This image is from his new book, Crabs and Shrimps of the Pacific Northwest.

The spines were in fact very important to the swimming ability of the zoeae.  Zoeae who had their front (anterior) spine removed could not maintain constant depth in the water.  Zoeae who had their posterior spines removed could not swim backwards or change directions easily and with both front and back spines removed the zoeae could not swim at all. This led Anna and Greg to conclude that the spines contribute to the superior swimming ability of porcelain crab zoeae.

Why is this important? This suggests that the carapace spines are not only used as physical protection from predators, as previously suggested, but also contribute to their survival in other ways. Anna and Greg also hypothesize that the ability to better control direction and water column depth helps the zoeae navigate currents and stay close to shore and may explain their limited dispersal offshore.

Citation:

Smith, AE, and GC Jensen (2015). The role of carapace spines in the swimming behavior of porcelain crab zoeae (Crustacea: Decapoda: Porcellanidae).  Journal of Experimental Marine Biology and Ecology, 471:175-179.

If you want to learn more about the crabs and shrimps along our coast, check out Greg Jensen’s new crustacean guide Crabs and Shrimps of the Pacific Northwest.

To learn more about this course and others offered at BMSC, check out the University Programs website.

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Registration open for “Field Skills for Undergraduates” 2014

by Amanda Kahn

What I got from my undergraduate degree was a lot of knowledge about biology but not a lot of hands-on skills.  I got those from taking field courses and working as a research assistant.  BMSC has just opened registration for a field skills training course, which will run from February 8-11 and 15-18, 2014.  You’ll learn field skills that will make you more competitive when hunting for jobs as a summer field assistant plus you’ll meet some folks at BMSC who can help you find those opportunities.  Check out the flyer below and visit the BMSC web page for the course for registration information.

field-skills-2014-poster

Coastal Field Archaeology course to host a Community Day at BMSC

By Iain McKechnie

The 2013 Coastal Field Archaeology course on an intertidal gradient. The 2013 Coastal Field Archaeology course on an intertidal gradient.

Coastal Field Archaeology is a 6-week university course being run through the Bamfield Marine Sciences Centre with the support of the Huu-ay-aht First Nations. We are working in Huu-ay-aht territory on the south side of Barkley Sound on the west Coast of Vancouver Island. We are here to learn about archaeological fieldwork and field research in coastal British Columbia in general but are doing this by learning about archaeological sites and Indigenous histories in Huu-ay-aht territory in particular. While there are a large number of previously surveyed and recorded archaeological sites in the territory, only a tiny fraction have been investigated by archaeologists. We are adding detail to this history by working at three previously known archaeological landscapes identified as significant places by Huu-ay-aht elders and government officials. This research aims to contribute archaeological insight into the human and environmental history of these places and further demonstrate the enduring continuity of Huu-ay-aht occupation and terrestrial and marine resource use with a particular focus on the period since European explorers arrived on the coast in the 1770s.

With the guidance of Larry Johnson, Director of the Huu-ay-aht Lands and Resources Department, the support of the Huu-ay-aht executive council, as well as the Bamfield Marine Science Centre and its five member universities (UVic, UBC, SFU, U-Calgary, and U-Alberta), we are extremely fortunate to have this educational and research opportunity. We are 14 students mostly from various BMSC member universities, two Huu-ay-aht youth from Anacla, two instructors, and a teaching assistant.

We have just completed our fourth week of fieldwork and this week we surveyed dense forested terrain near Bamfield and documented several sites including previously unrecorded culturally modified tree features and ancient habitation and resource use sites (shell middens). We were generously assisted in the field by Huu-ay-aht archaeologist and forestry survey specialist Stephen Smith (centre with the hardhat) as well as Bamfielder and current MA Student in Anthropology at UVic, Stella Wenstob, (in yellow on right). We are also getting the opportunity to visit a few incredible Huu-ay-aht archaeological sites both inland and on the coast including the 5,000 year old site of Huu7ii in the Deer Group Islands.

In the field.

In the field.

This Upcoming Friday (August 23rd), our class will be hosting a lunch for Huu-ay-aht community members at 12:30pm. Just after lunch around 1pm, we will be opening up the Ross Lecture Theatre

(in the cafeteria building at BMSC) to present an interpretive display of our findings as well as show off the equipment and techniques we are using to conduct archaeological research in the territory.

We invite everyone to stop by and learn about our work after 1pm – locals and visitors alike – as well as other researchers and staff at BMSC. Coffee and cookies will be served around 2:30pm and the display tables will be up until approximately 3:30pm.

Please do come visit us next Friday at the Ross Lecture Theater in the cafeteria building at Bamfield Marine Sciences Centre. THANKS FOR YOUR SUPPORT!
Photo Caption:
The 2013 Coastal Field Archaeology course on an intertidal gradient.

Free R Workshop at BMSC

by Amanda Kahn

Figure 1. A line graph at a  30 degree angle.

Figure 1. The workshop will likely focus on making data plots, and other R basics.

Guest speaker Allan Roberts from Ocean Networks Canada will be presenting a workshop on R, a versatile statistics package that’s useful in the marine sciences and related disciplines. For a summary of recent data workshops which were held at UVic in July, click here.

R Workshop
The day: August 1, 2013
The hour: 7:00 PM
The location: Rix Classroom C
What to bring: a computer with R installed (preferably R Studio)
Free for everyone.

The Neglected R


By Dr. Isabelle Côté

<i>Edit: Charlotte’s podcast is now correct, sorry for the error!</i>

Remember the three ‘R’s?  Reading, (w)riting and ‘rithmetics – the pillars of any education.  When it comes to science, I think that one more R is needed: the ability to Relate discoveries in a way that captivates rather than bores the listener.

Scientists are told over and over (and over) again that they cannot communicate.  We use too much jargon and provide too many details, which makes us incomprehensible to most people.  There are two possible ways to react to this criticism: stop trying altogether or try harder.  The second option has been my choice for the past year or so. I’ve attended communication workshops, created websites, started tweeting and blogging, all in an effort to learn to communicate science more clearly and effectively to a broader audience.

Of course, this enthusiasm for ‘sci comm’ is spilling over into my teaching.  The students on this year’s (2013) Marine Behavioural Ecology field course have been at the receiving end of it.  In three weeks, they’ve each given two formal and one informal presentations and had the chance to write, and then re-write, in the light of feedback, parts of their final report.  However, the one exercise that was new to all of them was the creation of a podcast – a 60-second recorded summary of a recent behavioural paper that they thought was particularly interesting.

What on earth can be the training value of a minute-long assignment? There are in fact lots of skills involved in making a good podcast. Students had to really understand their paper to be able to extract a single, most exciting nugget of new knowledge.  They had to write their piece, explaining the context, the question, the answer and the importance, in a jargon-free way ‘so that their grandmother would understand it’.  (Grandmas, by the way, are synonymous with an intelligent, interested, but non-specialist audience!)  They had to fit all of this in a mere minute, which involved a great amount of writing, pruning and learning not to get attached to their words. They practiced and practiced, listening and giving feedback to each other, experiencing the great value of peer review.  And they finally faced the microphone and recorded their pieces, and all agreed that I could post them.  So here they are (on SoundCloud):

Alex                            Charlotte                  Livia

Amy                           Christina                   Melanie

Anna                          Courtney                   Phillip

Brandee                     Ellika                         Shannon

Brian                          Erin                            Suchinta

Cathy                         Jasveen                     Susan

Chad                          Jessica                      Vivian

     Joel

It is likely that none of my MBE students will have a career in science communication, but given their keenness and ability for the subject, I anticipate that a fair few will stay in biology.  I hope that this little foray into how to make science popular and accessible will encourage them to explore how they can best master the fourth R.

Isabelle and the Marine Behavioural Ecology class of 2013

Isabelle and the Marine Behavioural Ecology class of 2013

R Bootcamp 2013 at BMSC

A beautiful Sunday in Bamfield (photo credit: Gillian Walker).

A beautiful Sunday in Bamfield (photo credit: Gillian Walker).

By Christina Suzanne

This year’s R bootcamp ran from March 3-7, 2013, immediately following the
Pacific Ecology and Evolution Conference (PEEC 2013). The workshop was
taught by Dr. Jean Richardson and Dr. Brad Anholt. The participants
ranged from R novice to R veterans; however, everyone learned something
useful and new! The five intensive days covered such things as data
input/output, managing data, scatterplots, error bars, maps,
multi-panel figures, t-tests, ANOVA, multivariate analysis, mixed effect
models, and much, much more! It also introduced various R packages, including ggplot2, vegan and lme4. Everyone left the workshop feeling much more
confident in R, and willing to tackle their own statistical problems using
R. Attending a future R bootcamp at BMSC is highly recommended to anyone who wants to start learning the R language, or increase their understanding of it!