Fab four Phyla part one: Echinoderms

When we take groups out tidepooling they are going to see a lot of new and interesting animals and 80% of these animals fall into one of four different phyla.  Phyla are on of the levels of classification scientists use to  where the broadest group is a Kingdom and it increases in specificity until you reach the species level.  All together you have Kingdom, Phylum, Class, Order, Family, Genus, Species.  We rarely use scientific names when referring to animals but we like people to know the four main phyla that we see on our beaches.  Our fab four phyla are Cnidaria (anemones and jellies), Arthropoda (crabs, shrimp, barnacles), Echinodermata (urchins, stars, cucumbers) and Mollusca (clams, octopus, snails).

As the name implies, Brittle Stars lose their arms very easily

The first phyla I'd like to talk about is Echinodermata.  Echino means spiny (think of an echidna) and dermata refers to skin (as in a dermatologist) so Echinoderm translates to "spiny skin".  Sea urchins are the eponymous animal for this phyla and don't outwardly resemble their cousins, sea stars and sea cucumbers.  However, all Echinoderms share the distinct characteristics of pentaradial symmetry, the ability to regenerate, and water vascular system that enables them to move.  

A beautiful Rose star

For our groups, Sea stars are the most popular invertebrates and people are always excited to see them.  This works out since there are a lot of cool things we can show people about them.  Sea stars have a dot on their dorsal side called a madreporite or mother pore which serves as a hydraulic intake valve.  By pulling in water through this pore they are able to move their tube feet which act as tiny suction cups.  They use this hydraulic action to pull open mussels and clams and eat them.  Once they have a mussel shell open even a millimeter, the sea star will slide its stomach out of it's body and inside the mussel shell in order to eat it.  Sea stars also have tiny pinchers called pedicilleria which allow them to protect the gills that cover their dorsal side.  They don't want kelp or barnacles to settle on them and the pedicilleria defend this vulnerable spot.  These pinchers are strong enough to tear out arm hair (as I often demonstrate) or they can also be used to attach a sea star to a kid's fleece.

Stimpson's Sun Star

Urchins, the next member or this group, are not nearly as dangerous here as they are are in tropical waters.  Our urchins don't have poisonous spines and are completely safe to handle.  Urchins eat algae using their five teeth and their tube feet are extra long so they can extend past their spines.  Urchins are also capable of seeing color, though this ability is not well understood by scientists.  They have proven in experiments that urchins are able to associate color with food and that urchins can see the entire color spectrum but they are unable to figure out how the urchins can see.  

 

A True Star nestled amongst Green Urchins

The last member of the Echinoderms is the sea cucumber.  Although not readily apparent, sea cucumbers also have penta radial symmetry if you stand them on their ends like a cylinder.  They also have tube feet which they use to hang onto the rocks and mud they bury themselves in.  The cool fact about cucumbers that we quote endlessly to our groups is their ability to eviscerate themselves to distract predators.  They will spit out their guts as an offering/distraction if something is harassing them enough and then they will regrow their insides if given enough time.  Sea cucumbers eat by pushing their mouth parts out in a feathery fan which they can use to collect plankton and other detritus out of the water or mud.  

Sunflower Star

The largest member of the Echinoderms that we find in our tide pools is the sunflower star.  These stars can often reach three feet in diameter and have up to twenty four arms.  Compared to the other sea stars, sunflower stars are extremely soft because they are holding more water.  They use this extra water to operate more tube feet (over 15,000 of them!) and can move much faster than other sea stars because of this.  They are extremely voracious predators and will often eat other sea stars when given the chance.  Because their body is so soft, these creatures prefer the lower inter-tidal zone and cannot be out of water for very long.

Sunflower Star's tube feet

Homer, Alaska

I just arrived here in Alaska last week but things have been busy from the get go.  I'm in the town of Homer, on the Southern coast of Alaska, working for a non-profit called the Center for Alaskan Coastal Studies (CACS).  CACS focuses mostly on educational programs featuring the incredible forests and coastal regions around Homer.

Jackalof Bay, one of the sites we tidepool at

Homer is situated on Kachemak bay, just off of Cook Inlet, which has some of the biggest tidal differences in the world.  On extreme days there is a 28.5 foot vertical tidal change which makes for some incredibly dramatic and amazing tide-pooling.  There are two sites from which we run our programs; on the Homer side we have the Wynn Nature Center which has hiking trails running through some amazing spruce forests and is much easier for people to get to since it has road access.

Cooking dinner in dutch ovens up near the Wynn

The Peterson Bay Field Station on the other hand, is only accessible by a 30 minute boat ride across the bay and is where we do the majority of our school programs.  We have also contracted out to the Kasitsna Bay Laboratory, a facility run by NOAA and UAF, that allows us to take more school groups into the intertidal regions.

Kasitsna bay lab, an extremely nice facility

The first program I was able to jump in after I arrived was the last of our winter programs this year.  We had a group of girl scouts come out who participated in things such as survival skills, snow shoeing and star gazing.  Mostly I hung in the background, as these programs were new to me, and observed two naturalists here, Patrick and Jenni, do a really great job teaching.  The kids had a great time and learned a lot and so did I.  The day after we returned we were already preparing to head out again, this time to the Kasitsna bay lab where we had a small school group from Palmer, Alaska meeting us.

Building telescopes to look at the stars

In an unanticipated bonus, there was a Tribal Marine Science Workshop going on at the lab hosted by the Seldovia Village Tribe and due to a low attendance we were offered spots in the workshop.  Because of this, we went to the lab a couple days before our school group arrived so we could attend all of the lectures.  The lectures included topics such as the decline of the harbor seal population, oceanography, ocean acidification, paralytic shellfish poison, plankton and marine invertebrates.  We had experts and phd's from all over the place giving us these lectures and it was really an amazing experience.  There were also some good negative tides during the conference and we used the opportunity to head out to the beaches and examine possible scientific survey techniques.  I was pleased to find that I remembered most of the marine invertebrates that I had learned about during previous seasons working up here.

Laurel, one of our naturalists, bundled up to go tidepooling

Our school group consisted of just a few students from an advanced science course and when they arrived they attended the remaining lectures with us.  The kids were great and intellectually curious so it was a lot of fun to take them out tide pooling especially since one of them had never been on a boat before.  They were certainly a strange group though, as they were coming from a tiny private school that had less than 50 students and had only a single student comprising their senior class.  In the past I've had groups come from islands on the Aleutian chain where the entire school might be made up of six students.  Because things are so spread out here a lot of children end up being home schooled or going to small group schools with a wide range of ages.  They definitely interact with people a little differently coming from such small communities but when you get down to it they are just regular kids.

Good negative tides create a lot of places to explore

We were a little worried towards the end of our trip because the weather kicked up and flights and boat trips were cancelled going across the bay but in the end were able to make it out during a window of calm and had a nice trip back across the bay.  I head back across the bay in a couple of hours with a boy scout troop; the aim being to make sure our field station at Peterson Bay is up and running and ready to receive school groups.  Peterson Bay is where I'll be spending most of my time for the next five months and I'm really looking forward to getting back over there.

It was cold out there