Invertebrate Spotlight: Larvaceans

Mucus house of a Larvacean

Invertebrate Spotlight: Larvaceans

By Michelle Marraffini

Invertebrate Zoology Lab

Today in the Marine Invertebrate Zoology we learned about one of the most interesting marine animals.  Larvaceans (Class Larvacean) are unique animals in the phylum Chordata along with their close relatives sea-squirts (Class Ascidiacea) and slightly more distant relatives humans (Subphylum Vertebrata).   These chordates retain their tadpool larva form and excrete a mucus house from specialized cells located on their head.  This house starts off as a small balloon like structure, the tadpole Larvacean whips its body to inflate the balloon with water, then when it is big enough the animal crawls inside, and whips its tail to continue to inflate the house.  Larvaceans will also eat with the help of their house which also contains screens set up to filter water, water is then further filtered by the animal so that it can eat bacteria sized particles.

A schematic of a larvacean in its house with the screens and showing water current flow. Photo Credit: Earthlife.net

They live in this house until the screens become clogged and then they swim out of it start to make a new one.  They discard their old house with sinks to the ocean floor as marine snow.  Marine snow is considered a big source of nutrients to the deep sea, to learn more about how larvaceans contribute to marine snow check out MBARI’s website.

Larvacean photo, screens shown in red tint, white folds are more filtering tools, and the animal itself is in the center of it’s house. Photo Credit: Arctic Exploration 2002, Per Flood, NOAA/OER

‘Spot a Basking Shark’ Project. How can you help save this endangered shark?

You can help the PSRC collect information to save the Basking Shark! Photo by Greg Skomal

By Kristin Walovich, Pacific Shark Research Center

Contrary to Hollywood’s portrayal of gigantic man-eating sharks, the three largest species of shark spend their time peacefully roaming the ocean’s surface munching on the ocean’s smallest creatures.  Basking Sharks, the second largest species of shark, cruise the seas in search of plankton, filtering up to 2,000 tons of water across its gills per hour. Reaching lengths of thirty five feet, this shark exists worldwide, yet very little is known about how they live or where they go.

To discover more information about this vulnerable species, scientists from the Pacific Shark Research Center (PSRC) and the National Marine Fisheries Service (NMFS) have begun a new type of shark hunt. Unlike the crazed and frantic scenes from the JAWS movie, this shark hunt only requires a boat, camera and telephone! The Spot a Basking Shark Project enlists the help of local sea-farers to uncover the demographics and distribution of the California Basking Shark.

Once common along the California coast, these gentle giants are now a rare sight. In the past, these social creatures were seen in schools of hundreds or thousands; however since 1993 no more than three basking sharks have been spotted together. Fishing and eradication efforts by fishermen who believed them to be ‘man-eaters’ contributed heavily to their population decline. Despite the fishery closure in the late 1950s, Basking Shark numbers have remained low, mostly due to human impacts like vessel strikes, fisheries bycatch and illegal shark fining. Based on the decline of Basking Shark numbers and lack of species information, the International Union for Conservation of Nature (IUCN) has listed this species as endangered.

If you see a Basking Shark, the PSRC and NMFS want to know! These sharks can be identified by their large size, pointed snouts, and large gill slits that encircle the head. Basking sharks have dorsal fins up to three feet tall that are visible as they slowly swim along the surface with mouths wide open catching plankton.  If you see a Basking Shark, call or email the PSRC with your location, date and time of the sighting and any photos or videos. Your information helps the PSRC document and understand these majestic and peaceful creatures.

Visit the PSRC Website to report a sighting and to learn more about Basking Sharks!

The basking shark can filter 2,000 gallons of water per hour while searching for plankton. Photo by Andrew Parsons

They’re BACK!

If you have been holding off on going to the Monterey Bay Aquarium until the sea otter exhibit re-opens…Now is the time!  On Saturday, March 23rd the exhibit was once again opened for the public.  I was there – and the crowd went wild!  Actually, there might not have been a crowd…I was too happy to notice!

What’s that on the rock?

What do you see on the rock?

What’s that on the rock?

By Michelle Marraffini

Invertebrate Zoology Lab

The invertebrate zoology class took a field trip to Asilomar State Beach last week to look for cool creatures.  Professor Jon Geller encouraged us to turn over rocks looking for flatworms, the topic of this week’s lecture.  As I overturned one rock I noticed something quickly hunker down.  It was this tiny octopus that tried to camouflage itself with the rock.   An octopus’s boneless body is well suited for changing its shape and its ability to mimic other animals, algae, and rocks or sand can be quite impressive.  Check out this video of an octopus camouflaging itself (‘Where’s the Octopus?‘).  These extraordinary animals are different from other camouflaging animals because they not only change their color and shadow but they also change the texture of their skin to match their background and they do all of this by sight!

Their very kein eyes detect the object they wish to look like and control over 30 million chromatograms (color producing cells) and papilla (cause the three dimensional shape of the skin).  Octopus’s do this while color blind which mystifies scientists.

Small octopus found at Asilomar State Beach hiding under a rock at low tide.

This octopus I found is likely a Pacific red octopus (Octopus reubescens), though it swam away before I could get a good look (no animals were harmed in the making of this blog post).  This is so far the coolest creature I have seen in the intertidal.  Get outside and see what you can find!

My little buddy swimming away.

Whalefest 2013 this weekend at the Monterey Old Fisherman’s Wharf

Celebrate the return of the Grey Whales to the Monterey Bay at the Whalefest Monterey 2013 event this weekend Saturday, January 26^th and Sunday, January 27^th !

This event aims to bring public awareness to the marine non-profits that influence the Monterey Bay Marine Sanctuary by offering a variety of fun activities, events, and exhibits from over thirty organizations.

Our very own Pacific Shark Research Center will have a booth set up this weekend!  Find us at the Causeway at Old Fisherman’s Wharf from 9am to 5pm.

The grey whale makes one of the longest annual migrations of any mammal, traveling nearly 5,000 miles from its northern feeding grounds to warmer winter calving grounds. Photo: Julian Pye

 

 

Life After MLML: News from the tropics

By: Michelle Marraffini

Invertebrate Zoology and Molecular Ecology

After graduating from MLML, former students go on to do great research at their new jobs or in Phd programs.   One of these former students is Paul Tompkins of the phycology lab, who took a phd position at Leibniz Center for Tropical Marine Ecology (ZMT) in Bremen, Germany.   Paul is conducting research the Charles Darwin Research Station in the Galapagos.  Beyond the famous finches and the oldest tortoises, the Galapagos also boasts an impressive marine system protected by their national park.   As part of a larger, ongoing project Paul is studying the role of algae in the food web and the response to climate change including El Nino events.

Spotted rose snapper (Lutjanus guttatus) and other Galapagos reef fish during a dive at Punta Nunez
Photo by: David Acuna

While collecting preliminary data of the system, using underwater transects and estimates of percent cover, a diver (David Acuna) helping Paul monitor Punta Nunez came across a fish species he did not recognize.  The possible identity of this fish is the species Lutjanus guttatus, Spotted rose snapper, which was cited for the first time in the Galapagos from catch data in Puerto Villamil in pervious years.  If the identity of this mystery fish is confirmed it would be a new record of the species and help scientists monitor populations of fish in the area.  It just goes to show that you always have to keep your eyes open for new discoveries.

A close up shot of the spotted rose snapper. Photo by: David Acuna (Charles Darwin Foundation)

8 Days at Sea

By Kelley Andrews, Pacific Shark Research Center

The high-pitched whine of the winch jolts me awake.  I come groggily to my senses, noticing the cigarette smoke from some of the crewmembers wafting through the door of the bunkroom and the dim morning light.  It’s somewhere around 5:45 am.

It is my third morning out at sea.  I am on the F/V Noah’s Ark, volunteering for a leg of the National Marine Fisheries Service (NMFS) Fisheries Research Analysis and Monitoring (FRAM) survey.  The mission of the survey is to assess the health of groundfish populations off the west coast of the United States.  The survey makes two passes of the coast from Washington to Southern California every summer, fishing and taking samples and data.  I am part of a team of three scientists, and we are with a crew of four fishermen on the 80-foot vessel.  Right now we are somewhere west of Monterey, CA.

Snail fish.  Photo: K. Andrews (2012)

The first tow of the day begins around 5:30 am, so we can begin processing the catch by 6:30.  The winches deploy and reel in the net from depths over 1,000 feet.  As I go out on deck to get ready to sort fish, I notice that the weather has picked up.  The first two days were flat calm, and I had no idea the ocean could be glassy 50 miles from shore.  But today the winds and swell are picking up, and it feels as though we are headed for rougher weather.

What Does a Vampire Squid Really Eat?

Researchers at MBARI have discovered that the vampire squid (Vampyroteuthis infernalis) doesn’t share a diet with its bloodthirsty namesake. In a recent news release, it was announced that this scary-sounding cephalopod actually feeds on the remains and waste of animals and microalgae that live in shallower waters. This “marine snow” falls through the water column to deeper water, where the vampire squid can pick it up using its unique features. The recent study observed that this creepy creature extends one of its long, thin filaments (which can be 8 times its body length!) to capture floating debris and bring it back towards its body. The vampire squid then scrapes the filament clean with its tentacles, which produce a mucus that sticks the food particles together. This is one ‘vampire’ that’s less scary than it looks!

The vampire squid isn’t as bloodthirsty as it’s name implies.
Photo copyright 1999 Brad Seibel

For more pictures, check out MBARI’s web page dedicated to the vampire squid, here.

Are you my clone?

One’s a lonely number
Photo courtesy of Catarina Pien

Ever wonder why you see some anemones in groups and some alone in tide pools? Sea anemones can reproduce in two different ways, asexually and sexually. Anemones are broadcast-spawners meaning that they release eggs and sperm into the water column for fertilization.  However if you’re an anemone that has settled onto a nice barren rock and don’t have time to reproduce, but you want to prevent other anemones  from taking over that rock  you claimed, what do you? You split yourself through…….. FISSION! This is asexual reproduction, where the anemone splits itself and creates another one of itself of the exact same genetic material.

Scenario of how anemones undergo fission from:
Sebens 1980 Biol Bull 158: 370; Sebens 1983 Pac Sci 37: 121; Ferrell 2005 Oecologia 142: 184

Depending on species this process may take days to weeks, but once there are more clones present, more can divide themselves through fission. Sooner or later you’ll see whole colonies of anemones on rocks!

Holy moly anemones! Each one of these are identical clones.
Photo courtesy of Catarina Pien

In the intertidal zone one of the limited resources is space for sessile organisms so anemones have adapted a way to populate an area quickly . But what if that pesky neighbor anemone is also asexually reproducing right next to your clones? What would you do? That’s when you take drastic measures, by fending them off with your acrorhagi, specialized stinging cells used to deter other anemones from taking over your area.

These battles are intense, both parties may suffer serious damage. As you can see in the video, the anemones when attacked retreat. This is because each one of those tentacles have stinging cells called nematocysts. Animals in the phylum Cnidaria (anemones, corals, jellyfish, and hydrae are part of this group) have these specialized cells.

Here’s a close of up what a nematocyst looks like magnified.

Nematocyst diagram from http://reefworks.co.uk/articles/feeding-techniques-in-cnidarians/

There is a mechanism that triggers the release of this harpoon-like contraption, when released the harpoon penetrates into the target organism and releases the toxin which is useful to immobilize prey such as fish. If you’ve ever been stung by a jellyfish that’s what exactly is happening; some species of jellyfish such as the box jelly and sea wasp have stings that cause excruciating pain, anemones also have these nematocysts too. However, because our skin is too thick for the nematocyst to penetrate into, you only feel a sticky sensation from touching anemones in the tide pools. The fact that we’re immune to most anemone stings in the tide pools doesn’t make it acceptable to touch them constantly though, the nematocysts do take quite a lot of energy for these anemones to regulate these mechanism. So the next time you’re visiting the tide pools do the anemones a favor and just observe and be amazed at their adaptations for surviving in the intertidal zone!

We maybe small, but please respect us!
Photo courtesy of Catarina Pien

That’s a Moray!

The exciting thing about science is we still have so much to learn about the natural world, new discoveries are being made all the time.  Rita Mehta at UCSC has been studying eels, specifically their pharyngeal jaws (see a video here), which are a second set of jaws that help the eels eat larger prey.  Recently MLML helped UCSC researcher Rita Mehta and others to determine how many California moray eels are in an area of Catalina Island, part of the channel islands archipelago.  Further, they are interested in growth of individuals and movement.  They had help from people at the National Oceanic and Atmospheric Administration (NOAA) with using Passive Integrated Transponder (PIT) tags, acoustic tags and acoustic receivers to address eel growth and movement.

UCSC researchers Ben Higgins and Leith Miller measure a California moray.

Using traps, eels would be raised to the boat then a series of body measurements and total weight were taken, they would be PIT tagged and released in the area of capture.  If they caught an individual again who had previously had a PIT tag, they could use the body measurements from before and compare them to the current measurements to learn  how much they grew in that time period.

Eels were caught and then brought to the boat for measurements using these traps.

To learn more about eel movement, a subset of eels had an acoustic tag surgically implanted into them.  Acoustic receivers were deployed at each cove which would detect the surgically implanted acoustic tags in the eels, if they were nearby.  They believe that moray eels may go out to feed during night but not much is known.  In two weeks, with over 300 unique eels measured and PIT tagged, you could imagine how dramatic and important an impact they have on the ecosystem!

Acoustic receivers were deployed in each cove to aid in understanding moray eel movement.