The Secret Lives of Sponges Revealed: Introducing Dr. Sally Leys!

They come in all shapes and sizes, some capture prey, some even sneeze…

Dr. Leys is a professor in the Department of Biological Sciences at the University of Alberta, and is one of the world’s foremost experts on one of the world’s most ancient Phyla: the Poriferans.

CB: Describe your research interests in a nutshell (think filbert rather than brazil).

SL: I’m interested in how animals sense and respond to the environment (in air or in water) and how the mechanisms to do this came about (in evolution). I assume that the ability to do this efficiently would have enhanced the success of the first animals, and therefore led to the evolution of more complex systems (sensory, neuronal, tissues, and body structures). This really boils down to the question of how sensory cells and nerves evolve. I study how animals coordinate behaviour without nerves, in order to evaluate (try to determine) whether these mechanisms formed the basis upon which the nervous system arose.

CB: You work primarily with sponges as a model system.  What are your main reasons for doing so?

SL: Sponges are the only animal group that lacks nerves or muscle. They are able to coordinate and to move (very slowly) but they never went down the path to nerves and rapid movement. Therefore sponges can help us understand how cells communicate when nerves are absent (for example in the case of diseases that attack the nervous system, or where nerves have been damaged, or even simply in the glial cells of the brain, which communicate by calcium signals). Sponges are also considered the most ancient phylum (Porifera), and the sponge body plan is not thought to have changed much in the last 800 million years. Therefore from studying modern sponges we can hope to understand what building blocks were present in the earliest animals.

But really, Sponges are cool.

There are no ‘rules’ to being a sponge. I just saw some photos of deep sea sponges that were like large baseball mitts perched up on a thick smooth stalk that looked like it was made of yellow plastic tubing; another was a simple white stalk with a perfectly symmetrical crown of spikes at the top (that one was carnivorous!). Sponges can filter bacteria, and can capture and eat shrimp; they can live in deep oceans and in shallow rivers and lakes, and even in sand dunes! They offer homes to so many other invertebrate and fish, and they’re extremely colourful. They are simply irresistible to work with.

CB: It always annoys me when people state that Cnidarians don’t have brains.  Your work on coordinated movement in sponges surely demonstrates that they have some kind of nervous system doesn’t it?  What are your thoughts on this?

SL: Well, first…I would agree that cnidarians don’t have brains as such, in the way that we usually understand a brain — a complex structure of neurons and supporting cells localized in one spot. Perhaps that concept of a brain is overrated. Cnidarians have complicated nervous systems but usually it is more spread out to reflect the fact that many cnidarians receive signals from 360 degrees, and therefore coordination is via a network of neurons that allow the animal to respond to stimuli at any point in a coordinated way. Poke a jellyfish and it knows which side you’re poking it on, and (depending on the type) will jet away in the opposite direction.

However, you don’t need nerves to have coordinated movement. The Venus fly trap and Mimosa plants close their petals and drop their leaves to trap a fly or expose thorns to predators, and they don’t have nerves. Rapid movement needs electrical signaling (an action potential) which requires a conduit that electrical current can rapidly travel down. All that is really needed is a fluid connection between cells, and in the plant a chloride potential travels quickly through the plasmodesmata (connections between cells) to all parts of the plant.

Sponges are animals that don’t have nerves, but some of them do use action potentials (electrical signaling) to coordinate arrests of pumping. Sponges make a living by pumping water through tiny canals and a fine filter to capture bacteria and other small food particles, and to get oxygen and excrete wastes.

Only one group of sponges (glass sponges) can stop their pumping instantly, and they probably do this to prevent clogging the filter when the water is really full of sediment. Glass sponges (hexactinellids) can do this because their tissue consists of a giant single cell, and therefore electrical signals can travel through the cytoplasm of the entire animal without encountering any membrane (electrically insulating) boundary. The action potential is slow (about 5s long) and it doesn’t trigger any contractions (glass sponges don’t seem to be able to contract at all). Instead it triggers calcium to enter into the cells that have flagella which whip back and forth to generate the pump. The calcium stops the pump, and the water stops moving through the sponge. Only when the calcium is sequestered into compartments again does the sponge begin pumping.

Most sponges are cellular – and these cells don’t have a way of passing electrical signals (they are not nerves and don’t appear to be ‘coupled’ electrically). So what seems to happen is that they when they sense some change (could be a change in flow around them) calcium enters one cell, and that causes the release of a chemical which triggers calcium to enter into the next cell, and so on until the wave of signal and response has moved across the whole sponge. We think this occurs by calcium because the behaviour is very slow. We see a sponge sneeze for example (ahhhhh choooo) in about 20 minutes.

CB: The bulk of your work takes place in a lab setting, do you culture all of your own sponges or do you collect them from the field?

SL: We do both. For most work we need to collect sponges from the field…and work with them there. Sponges are picky, and sensitive to water quality, and know if the flow in a tank is poor or the food different, and that makes them pump less and eventually not do very well. So for many questions we need to study them in the field. We then also need to collect fresh pieces of sponges to preserve for studies on genes or structure. But, for some of our work we have found that it’s really easy to hatch out and culture a little freshwater sponge in Petri dishes in the lab. Freshwater sponges have a habit of forming little millimeter diameter balls or cysts in the winter. We keep those in the fridge and hatch a sponge from them whenever we want to study the sponge’s behaviour (like its sneezing response).

CB: You are doing some work on the unusual Glass Sponges in British Columbia.  What does your work involve?  Is there a conservation concern here?

SL: We are mapping the extent of the reefs in the Strait of Georgia, specifically one at the mouth of Howe Sound, one near the outflow of the Fraser River and one near Galiano Island. We’ve mapped them to know how much of the reef is made up of living and how much of dead sponges, what other animals live there, and to understand how they grow so we might be able to predict how best to protect them. We’re also studying their reproduction and trying to determine whether individuals beside each other arise from budding off of neighbors or if they have come in as larvae from other reefs. This will help us understand if all the reefs are able to replenish each other, and have a good genetic mix, or if they really rely on local sponges for new recruits and for continued health.

The reefs are a major home for crabs, shrimp and fish (less so for other invertebrates it seems, although worms are abundant in the mud of the reef framework below the live animals). Since these are commercially important animals on the BC coast, we can infer that the sponge reefs play an important role in maintaining healthy populations for fisheries. At the moment our work represents a base line of data and a regular monitoring program (and even tagging, and recapture program) would tell us whether the reefs are nurseries for fish, and replenish populations elsewhere.

For a long time we have also been studying how the sponges feed, what they feed on, and what role they play in the capture of nutrients from the water column and recycling of carbon and nitrogen o surface waters. It turns out that the reefs filter vast amounts of water each day (a 1km stretch of Galiano reef filters about 83,000 Litres each second), so they are clearly massively important to the local water. What would happen to the quality/content of the water in the Strait of Georgia without the sponge reefs is completely unknown. Probably a lot of carbon would end up as sludge on the bottom, and not be returned to surface waters for use by plankton.

So you can see that although we don’t study conservation directly, we aim to provide basic information that will allow DFO and politicians (and people in general) to make informed decisions – hopefully to protect the reefs and thereby to protect our waters.

CB: What’s a typical work day like for you?

SL: On typical a week day I’ll bike in to the U of A with my husband, who heads off to teach at a high school. I usually spend the first hour or two reading and responding to mail, and dealing with administrative things. I then either start work with one of my students (when they get in!), either in the lab or in another lab. I do a lot of lab work, often with one of my group. We might do an experiment on the microscope, or extract RNA for molecular work, or fix or process tissue for electron microscopy. I’ll often consult with one or more of my colleagues, either locally or by skype during the morning;  I work with people all over the world, so this can happen at different times of the day. Then I may meet with one of my group to discuss a thesis chapters or a paper we are working on; that can take a couple of hours, and then it’s back to either some more lab work or reviews of papers or literature searches. I usually have a spinning (biking) class or go to the gym in the late afternoon, and then bike home. At home, I’ll do some gardening and catch up on the day with my husband and on the news on the radio and TV…and read.

A work day at Bamfield is nearly the same but involves a morning kayak rather than a bike, and possibly an afternoon sail instead of the gym! On different days we’ll dive for collection, and I’ll spend a good amount of time fiddling with aquaria working at the microscope, and talking with colleagues and staff.

CB: What is your most recent publication?

SL: Hot off the press is the sponge genome paper, which we just got the proofs of from Nature. This is the culmination of about 10 years work by a lot of people to sequence the first genome of a sponge. The sponge, my pet, was one I found at Heron Island in 1998, so I am quite fond of it!

CB: So exciting, congratulations! Here is a PDF:  nature09201

My other most recent paper is a cool study showing that the ‘neurotransmitters’ GABA and glutamate inhibit and stimulate contractions in the sponge. Who would have thought that sponge ‘muscle’ responds to the same stimulants and inhibitors as vertebrate muscle?

CB: Any advice to budding biologists?

SL: If you really want to do marine biology, then do what interests you most, and do it regardless of the any obstacles you might perceive. It might mean living where you didn’t intend to, traveling more than you thought you might, and working very hard, but the life is so rewarding, so variable and so flexible and so interesting that you will never have a dull moment.

CB: Do you have any non-biological talents?

SL: I love sailing – I grew up sailing, and it’s very much under my skin. We used to race when we were on the coast. Now, whenever there are just two boats on the water it’s a race! I garden, and I like to construct (build) wood sheds, walkways, things!

CB: If you could have 3 guests for dinner…alive or dead…who would they be?

SL: Hemmingway, Alfred Wallace, and Jane Goodall.

CB: What would you eat?

SL: Fish

CB: Thanks so much for taking the time Sally!  I’m humbled at the clear awesomeness of the Poriferans!

Nerds in Nature…Who’s on Holiday Anyway?

I was walking on the beach the other day in beautiful Parksville, BC, when I happened upon a crowd gathered around a group of busy scientists.  Never one to miss out on an opportunity to engage in some nerd-speak I thought I’d poke around and see just what they were up to.

Introducing J.P. Richards, a professor in the department of Earth and Atmospheric Sciences at the University of Alberta, and this week’s specimen in Nerd Corner!

It turns out that the group was digging deep into the vast sandy expanses of Rathtrevor beach in order to extract giant 7 foot cores of sediment.  The sediment cores will be shipped back to the university for a host of chemical and physical analyses that will provide evidence about the geological and biological evolution of the area.

Dr. Richards graciously took a few minutes from his work to answer some questions:

CB: What are you doing here??

JR: We are interested in the coevolution of the biological and geological systems in this area.  In the early 1900s the Englishman River avulsed (abruptly changed its flow pattern) away from this area.  At that time the geomorphology of this bay drastically began to change from an area of strong currents to one of quiescent deposition.  Our work here seeks to address how these geological changes affected the biota, we do this through examination of trace fossils from within the cores.  We’ll be able to determine the animals that were present over the past 100 years.  Our interests bridge the gap between geology and biology.

CB: Any advice to budding biologists?

JR: Follow your passion.  You need to do what you love.  Keep doing what you are doing until it’s not fun any more, and then try something different.  That’s the only way you’re going to be good at this business!

CB: If you could have 3 guests for dinner, alive or dead, who would they be?

JR:  I’d need to invite 4 people if that’s ok.  William Diller Matthew (renowned Canadian paleontologist), Nelson Mandela, and my two daughters, aged 2 and 6.

CB: I should have known you had young kids, my 3 year old daughter was thrilled with the ghost shrimp and crabs that you brought over to her!

CB: What would you eat?

JR: Smoked fish of all types.  Trout, salmon you name it!  Whenever we come to Parksville for field work our first stop is always to French Creek where we buy 4-5 varieties of smoked fish.  It’s my favorite thing!

CB: In addition to his academics, Dr. Richards runs a blog for the academic staff at the University of Alberta, ‘Whither the U of A’.  Thanks so much for taking time from your busy field schedule to chat with me Dr. Richards!

The Nerdiest Non-believer of them All – It’s PZ Myers!

You know him as the fearless and godless blogger behind Pharyngula, whose demands were quickly heard during his recent blogging strike to protest the chaotic happenings at Science Blogs…but do you know him like I do??

BFFs PZ and CB (look how happy I am...I'm such a dork!)

Dr. Paul Myers is a professor of Biology at the University of Minnesota, Morris.  There’s a LOT of info readily available on the net for our dear PZ with respect to his blog and his research interests, so I thought I’d ask some friendly questions to learn a little more about just what makes him tick…

By the way…this is a somewhat truncated version of Nerd Corner, seeing as there was a large and rather ravenous crowd stacked up behind me eagerly awaiting their chance to speak with Dr. Myers after his recent lecture in Vancouver, BC.  I got there first though…SNAP!

CB: What’s a typical work day like for you?

PZ: When the semester starts, I’ll be teaching 2 courses with a total of 4 lecture sections and one lab section, so most days I’ll be spending about 4 hours on lecture prep, 2 hours in class, and a few hours each day dealing with students (the last bit varies: maybe 0 hours early in the term, rising to as much as 6 hours before an exam).  If I’m lucky, I’ve got a couple of students working in the lab, and I’m helping them figure out how to work with itty-bitty embryos. Then there’s the committee work, maybe a few hours a week, and the grading, which also varies week by week, and I often put it off to the weekend, when I can. And then roughly every other week, I fly off somewhere to give a lecture. So, basically, the middle of my day is entirely occupied with teaching.

I get up around 5:30, put in an hour or two throwing stuff together for the blog, which I schedule to appear during the course of the day, and once I get home I’ll putter about on the blog some more. I’ll usually get to bed around midnight.

CB: Any advice to budding biologists?

PZ: Right now if you study biology, you will often get sidetracked into the details, like mastering the biochemistry of the cell or something like that.  What students really need to do is step back and get a wider view of the field. Breadth is as important, if not MORE important than depth.

Pharyngula larva

CB:  Do you have any non-biology or blog-related talents or interests?

PZ: No, not a one. I’m a very boring person.

Actually, I read more or less constantly. Either I’m poring through some recent science papers, or when my brain is running a little slow, I’ll read a SF novel or two. I try to get some exercise by doing all my errands on foot — I live in a small town, so it’s entirely practical to go grocery shopping or banking or head off to the coffee shop without driving, so I usually put in a mile or three walking. I make it a point to go to the local movie theater once a week, no matter what’s showing…which means I’ve seen a lot of very bad movies.

CB: Hey good on you!  In another life I owned a small town movie theatre, it’s a tough business.

PZ: I’ve also played a bit of World of Warcraft now and then, but that’s had such a low priority that I’ve rarely gotten around to it anymore, and cancelled my subscription. Maybe some day I’ll have a little more free time…it’s not happening right now.

CB: If you could have 3 guests for dinner, alive or dead, who would they be?

PZ: Lenin, Darwin and Charles XII of Sweden

CB: Goodness!  That would be a boisterous table!  Darwin gets a lot of invites among my nerds!

CB: What would you eat?

PZ: I would make a phylogenetic stew, where you try to throw in as many phyla as you can…lots of seafood!

CB: Thanks for your time PZ!  I’ll see you on your blog