- Deep Sea Fauna
- Environmental Variability
- Consequences of DWHOS
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- DEEPEND Publications
Recent blog posts
Happy Tuesday from the middle of the Gulf where the temperature is hot, the water is like glass, and the sun is shining!
The past few days have been early mornings for all of us on the R.V. Point Sur. The nets come up around 3:30 -3:45 a.m. and the processing begins immediately and lasts between three to five hours! The scientists methodically sort out the specimens according to their specialty and the lab is flowing with scientific names! At first it was a bit overwhelming because I had no idea what all of the scientific names were (I was only familiar with the common names), but after a few days, multiple samples, and seeing the same organisms over and over, I’m beginning to recognize the various species.
We have been catching some pretty awesome fish, crustaceans, larva, cephalopods, and jellies. The colors of the animals are mostly black and deep red with many bioluminescent capabilities. The organisms are full of extraordinary photophores, tiny and complex light emitting organs, which allow them to emit bursts and pulses of light, whether it is for communication, mate attraction, or predator avoidance. Some of the photophores were still emitting light when we looked at them under the microscope! I will post some of those pictures tomorrow so stay tuned!
Below are pictures of some of the amazing critters we have been fortunate to observe. Some pictures I took and some were provided by our amazing photographer on board, Dante Fenolio.
The picture on the left is the cod end of the net where all the organisms are, and the picture on the right is an example of one net sample. Once it is poured into the container all of the scientists go through it and sort out the species they study.
Deep sea crustaceans! Deep sea squid, Abralia redfieldi
The picture on the left is of a female anglerfish! The females are the ones that have the lures, not the males. They typically use the lures to attract prey. The picture on the right is what happens when a styrofoam cup is submerged into the ocean 1500 meters! The pressure is so great that it crushes the cup to this minute size.
Tiny anemone larvae that we found in several of our samples today!
I will post more amazing pictures and information tomorrow! Thanks for following the teacher at sea blog!
Catch of yesterday morning...a lobster larvae.
Another encounter in the afternoon trawl. A Dragonfish (Idiacanthus fasciola). This Dragonfish is sexually dimorphic. Males don't get the barbel and bioluminescent bulb hanging off of their chins. They have short lives and last just long enough to breed. This is a female. Note the bioluminescent photophores on her sides. Those spots glow in the dark and most likely aid in recognition of same species individuals and even recognition between the sexes. The bulb at the end of her barbel glows and attracts her prey items.
A deep water fish (Scopelarchus analis) with upward facing eyes that are adapted to see faint light or to key in on bioluminescence.
Yesterday morning we deployed our drone - an "autonomous underwater vehicle or AUV." The unit will move to various ocean depths across the next two weeks and collect water parameters. When we are ready for it, we will signal for it to stop and go to the surface. It will then start "pinging" using a GPS unit and we will locate and retrieve it.
The sunset last night was gorgeous!
Our morning began nice and early at 2 a.m. with the deployment of the MOCNESS! This was our trial run to make sure that the apparatus works correctly. The net was down for about two hours and fished the top 200 meters. When the net surfaced it was safely secured on the vessel, the samples were collected and taken into the wet lab, placed in the sample tray, and the specimens were all processed. In our trial sample we found several species of fish including dragonfish, lanternfish, eels, over two hundred crustaceans, pteropods, a cephalopod, and many planktonic larvae. The trial run was a great snapshot of what is to come, which is extremely exciting and leaves me just wanting to learn and see more. The diversity that I saw this morning was simply incredible! To be able to see these organisms firsthand and not on a documentary or in pictures is such a rare opportunity and I can’t wait to share more with you over the next two weeks! There will be more cool species to report tomorrow once our sampling continues. We ran into a few technical difficulties that occurred this morning so hopefully we will be up and running tonight!
Emptying the trial sample. Pteropods, also known as Sea Butterfly's.
Over 200 Crustaceans were collected. Ceratoscopelus warmingii
After our trial sample and breakfast it was time to deploy the AUV. Charles Kovach, a research scientist at USF College of Marine Science, successfully deployed the University of South College of Marine Science AUV (Autonomous Underwater Vehicle) Glider into the Gulf of Mexico. Chad Lembke is the leader of the Gulf Glider Task Team at USF College of Marine Science and works collaboratively with GCOOS / GANDALF (Gulf Coast Ocean Observing System) which is based out of Texas A&M but operate regionally.
The Glider will be roaming the waters of the Gulf for the next 14 days and will be retrieved at the last site we sample. You can follow the AUV at http://gcoos2.tamu.edu/gandalf/. The AUV is programmed to surface every three hours and will travel up and down in the water column between 200-1,000 meters in the Loop current. The AUV provides scientists with real time data on key abiotic and biotic factors in the ocean such as chlorophyll, temperature, dissolved oxygen, salinity, conductivity, turbidity, and dissolved organic matter. The overall goal is to show a correlation between the chemical and physical composition of the ocean and how it directly relates to the strength and success of an ecosystem.
Until tomorrow my friends!
Greetings from the R.V. Point Sur! My name is Alisha Stahl and I’m your teacher at sea from Ellenton, Fl. It is such an honor to be chosen for this position and to be given the opportunity to work with some of the most distinguished scientists from Nova Southeastern University, University of South Florida St. Petersburg, Florida Atlantic University, Texas A&M at Galveston, and Florida International University. The research we will be focusing on over the next two weeks is developing a quantitative taxonomic assessment of deep sea pelagic species of the northern Gulf of Mexico in the region surrounding the Deepwater Horizons oil spill.
The R.V. Point Sur diligently set sail around midnight on August 8, 2015 with all 15 scientists and a multitude of crew members on board. Prior to our departure everyone spent the first few hours setting up their bunks or state rooms and getting settled in for the next 15 days. The rooms are spacious and comfortable with ample storage to keep all of our items, while the swaying of the Gulf’s waves rocked each of us into a deep slumber.
The first site is roughly 200 miles offshore resulting in about 20 hours of travel time on this gorgeous Saturday afternoon. The waves are about three feet high, the sun is shining, and the water is gradually taking on a gorgeous deep blue hue with sporadic racks of Saragassum floating by. The day was spent resting, going over protocol, and setting up the MOCNESS (Multiple Opening and Closing Net and Environmental Sampling System) net.
The MOCNESS is a unique apparatus consisting of several nets stacked on top of one another in a single frame which is then towed behind the boat. The scientists can manipulate the nets to open and close based on the depth in which they want to measure. During this research trip the net will be broken up into six different nets labeled 0-5. Net zero will be deployed, remain open, and sample the first 1500 meters, net one 1500-1200 meters, net two 1200-1000 meters, net three 1000-600 meters, net four 600- 200 meters, and net five 200 meters to the surface. Each tow will last six hours and then the samples will be processed according to protocols set by the chief scientist (Tracey Sutton). The benefit of using a net system such as the MOCNESS is that it allows scientists to study specific depth ecosystems more efficiently especially since the organisms living in the deep move a lot slower, making them a little easier to catch.
Can’t wait to share what we collect tonight during our first tows!!!
We finished up the last few sampling sites yesterday. Kendall and I can’t thank the group from Texas A&M and the Blazing Seven crew enough for making the cruise so enjoyable. I’ll miss my time on the boat, but I’m excited to return to my position at Sarasota High School and share my experience with my students!
Though it may take longer to sort through a sample inundated with sargassum, we’ve been seeing some really unique organisms. Pictured below is a sargassum fish, an ambush predator, that has the perfect camouflage.
We’ve also been collecting filefish, crustaceans, and jellyfish that are taken out of the samples by Carlos Ruiz and Veronica Quesnell.
Right after they help pull up the nets they search each sample for organisms to take back with them to the Texas A&M Galveston Shark Biology and Fisheries Lab run by David Wells, PhD.
Carlos came back to his alma mater of TAMU after finishing a M.S. from Auburn University. A research technician, he has an integral part in the lab and assisting graduate students on their projects. The position allows him to take part in a wide variety of research and to be out in the field frequently, which he enjoys. It would be a great opportunity after graduation for any student with an affinity for research .
Veronica usually isn’t out on the field, and instead gets samples for her research on swordfish from NOAA and commercial fisheries. Along with other courses she’ll be teaching fisheries techniques in a field ichthyology course. In addition to being a researcher, student, and teacher, Veronica is the mother to a beautiful girl named Abby.
We’ve had some exciting visitors in the past 24 hours. Last night we saw two pygmy whales, and a sperm whale and this morning a pod of dolphins.
Onto the fish! Picture the excitement of pulling up a Mahi mahi, the same thing happens here, but instead of holding up the fish with two hands these guys fit on a finger.
This tuna is distinguishable by the dark mark on its dorsal fin. When the fish is too small determine the species by sight scientists rely on DNA analyses.
The fishes below didn’t need DNA identification. The sailfish on the left, and swordfish on the right are starting to display characteristics of the adult fishes.
Each sliver of silver below is a fish to be sorted and collected.
Scattered in the samples are these copepods. Familiiar shape, but a striking color!
I’ve previously written about the large amount of sargassum in the water around us. As Jay Rooker, PhD predicted before we towed, when we were in clear water with a high salinity we started to see the billfish. On the left is clear blue water where we found mahi, tuna, and billfish. On the right the water in this picture is heavily influenced by the freshwater input of the Mississippi river which gives it a greenish hue. The salinity in this area has dropped down to 21 ppt even though we’re still quite a ways offshore (remember you can see where we are here).
Water from rivers brings with it nutrients creating prime environment for algae. We’ll be in this “green water” for the rest of the trip.
Yesterday was another beautiful day on the Blazing Seven. We’re still running across a significant amount of sargassum while using the neuston net. Our captain, Thomas Tunstall, tries to avoid the floating masses during the tows.
Deploying her own plankton net at every other site is Jillian Gilmartin. She came to Texas A&M (TAMU) from NC State with degrees in Meteorology and Marine Science. She just brought up a sample with lots of jellyfish. She explains that this area, the middle of the loop current, is warmer and has low biological productivity. Jillian is collecting the plankton samples for her thesis. Her research focuses on tropical species found in the Gulf of Mexico that arrive there via the loop current off of the Yucatan.
When I asked what I should tell my students who are interested in pursuing a career in Marine Science she suggested getting involved during your undergraduate degree by interning or working in a lab. The work she did outside of her major is actually what led to her current research with Dr. Rooker.
Cori Meinert is a brand new graduate student at TAMU. She is an Environmental Science major from Ohio that worked in a freshwater lab last summer. She came across an article by Dr. Rooker during her studies, emailed him, and then made the decision to start her Masters degree at TAMU. She had just arrived in Texas and then traveled the very next day to the ship for this research cruise. What a way to dive into your graduate degree! In the picture below Cori is recording the pH, salinity, and other characteristics of the surface water at each site.
Near the end of the day the sargassum started to clear. This time the neuston net sample contained the billfish that we had not seen in the previous tows.
One of the goals of this cruise is the research done by Jay Rooker, PhD and his lab on pelagic fishes, such as billfish and tuna. This ties in the data being collected by DEEPEND with information from the epipelagic zone. When I picture a billfish what usually comes to mind is the adult stage that recreational fisherman target for sport. It’s easy to forget that they all start out as zooplankton, and we’ve been finding a few in each of the tows. The image below depicts a sailfish on the top and a blue marlin on the bottom.
Attached to each of the plankton nets is a flowmeter, which looks similar to a rocket.
It measures the volume of water flowing through the net. This allows researchers to calculate the number of fish and other organisms collected per unit volume of water and make estimations about a larger area.
Since the neuston net is towed at the surface, it frequently contains large amounts of sargassum. Dr. Rooker explained that areas with high amounts of sargassum usually yield low amounts of these epipelagic fish. We saw evidence of this during our last tow.
This floating macroalgae is carefully searched for specimens by the group and then weighed. It’s been very impressive to see the sharp eyes of those around me pick out fish from a heap of sargassum no more than 1 mm long.
The tiny dot below is on the finger of Maelle Cornic, a PhD student. Maelle looks at early life stages of tuna in the Gulf of Mexico. She’s got some of the sharpest eyes on the ship and is consistently finding the smallest critters hiding in the sargassum. Maelle is from France, where she says being around water sparked her interest in fish from an early age.
Another PhD student in Dr. Rooker's lab is Mike Dance, an avid fisherman. Part of his research uses acoustic telemetry, a tracking technology using tags, to monitor the behavior of juvenile red drum in Texas estuaries. In addition to finding out where the fish are spending their time, Mike determines the type of habitat (oyster bed, seagrass, etc.). Mike focuses on red drum ages 2-18 months. Models based on the data collected will shed new insight into the nursery habitats of the fish.
Our last plankton tow of the night once again yielded a diverse group of organisms. Among those collected was a viperfish, Chauliodus sloani. Kendall is busy counting the photophores using a stereoscope that projects onto the computer. This allows pictures and video to be collected of organisms before they're preserved to help with identification later on.
When I left last we one more site to sample from, which was done at night with the help of flood lights on the deck. Once again the bongo and neuston nets were deployed. This last stop of the night stood out from the others since we deployed a bongo net this time reaching a depth of 500 meters. This sample was taken in the middle of the mesopelagic zone which spans vertically from 200 to 1000 meters. This zone is sometimes referred to as the “twilight zone”, because some light still penetrates. Fellow Floridian, Kendall Lord, has been a big help identifying the deeper living fish. He is graduate student and research assistant at Nova Southeastern University. He works with Dr. Tracey Sutton, his advisor and the DEEPEND Consortium Director. Kendall is working on his Masters degree in Marine Science. His thesis will cover the history of research in the bathypelagic zone (> 1000 meters below the surface). He’s using research starting with the 1870’s with reports from the HMS Challenger all the way up to the Census of Marine Life from 2000-2010.
One of the first organisms pulled out was a purple jellyfish that Kendall informed me was a Periphylla periphylla, the helmet jellyfish.
We also found a bristlemouth fish (Cyclothone sp.), the most abundant vertebrate on Earth! Some of these little guys are serial hermaphrodites, specifically protandrous, meaning they are males first and then turn into females. Clownfish change their sex in the same way.
Many of the zooplankton collected were either clear, red, or black. This is part of their camouflage to help them hide from predators. The red shrimp pictured below stands out amongst the other organisms on deck, seemingly a contradiction. The reason some organisms in the deep are red in color is because it doesn’t penetrate as deeply as the other colors. Those bright red shrimp actually appear black in the mesopelagic zone where we are sampling. The clear organism that you can see only part of in the picture above is a larval eel, or leptocephali.
Perhaps the most exciting organism collected was a heteropod. In hand it appeared to be a gelatinous blob. When placed into a small tank for observation we were able to observe the mollusk’s unique swimming behavior that earns it the nickname “sea butterfly”. You can see video here. This unique gastropod is quite the predator! We later witnessed it feeding on the eel larvae which was easily 10 times its size.
After collecting the samples we went into one of the labs to take pictures and sort the organisms into Whirl-Paks. The fish in the picture below is a hatchetfish.
We began again this morning around 6:30 am. The weather is fully cooperating and the plan is to get through 12 sampling sites today.
Greetings from the R/V Blazing Seven! I'm your current teacher at sea from Sarasota, FL. I'm very excited to be joining scientists and students from Texas A&M Galveston and Nova Southeastern University to sample the larvae and juveniles of pelagic fishes using plankton nets. You can read more about the research done by Jay Rooker, PhD here.
We left Port Fourchon, LA early this morning and just made it to our first sampling site to collect plankton. Plankton are tiny (usually) plants or animals that drift with the currents. The focus of this cruise is animal plankton, referred to as zooplankton. The basic design of a plankton net is a large area of mesh that ends in a collection bucket. The two nets we will be using during this cruise will sample at different depths and have different mesh sizes.
The first net, rightfully named a bongo net, is deployed from the stern. The reason it has two nets is that one net has a mesh size of 333 microns and the other has a mesh size of 500 microns allowing us to sample two different sizes of zooplankton. The bongo net is hoisted off the back of the boat using a winch. After entering the water it sinks down to a depth of 100 meters (328 feet)! When the nets are brought back up to the surface they are carefully rinsed with seawater to ensure that all of the organisms make it into the collection buckets at the bottom.
The second, a neuston net, is deployed from the side of the ship and samples at the water's surface.
Each sample from the plankton nets contain algae and a wide variety of of organisms from copepods to larval tuna. The samples are placed in a freezer for identification at a later date. We collected a larval tuna and a sargassum fish!
In addition to targeting larval and juvenile pelagic fishes, we are collecting samples for other labs involved with the DEEPEND Consortium for their research as well. I’ll get into that more later. Our next stop is coming up soon!
Blog posted for Jeff Plumlee:
Howdy from the Blazing Seven!
Success! We have completed our mission, with all gear intact, and two days ahead of schedule. We finished 12 stations today towing both the neuston and bongo nets. Our day started at station 37 at 06:00 hours and finished at 21:00 at station 48. Sargassum mats were still very present throughout the day but diminished towards the end. The majority of the fishes we had found in previous trawls, however, a few fish expanded our list of families, such as porcupinefish (Diodontidae) and pipefish (Syngnathidae). We continued to find billfish and flying fish larvae when sorting through the Sargassum mats.
Another group of people, aside from the scientists, that needs recognition for our success is our crew. Warm meals, posh rooms, and a fully functioning vessel, all are attributable to the hard work of the crew of the Blazing Seven.
Thomas Tunstall - Captain
All of them played many different roles throughout this trip, and all of them have put forth their best efforts to get us home safe and sound. Thanks again guys.
Well, this is my last update. We head home to Galveston, TX tomorrow morning with samples in hand. Stay tuned for our second ichthyoplankton cruise in July - we can only hope that it goes as smoothly. Cheers!
Blog posted for Jeff Plumlee:
Howdy from the Blazing Seven!
Day three turned out to be another beautiful day to be a scientist on the Blazing Seven. Flat seas, blue water, and warm sun have been a constant this trip, to our enjoyment. We began our day after making the trip from N 27 to N 28 and arriving at station 25 at 0600. Sargassum was yet again present in every tow save the last two and brought a bounty of fishes. It was the most we had seen yet, but with some new faces, including tripletail (Lobotidae) and Bermuda chub (Kyphosidae). We continued to find billfish larvae as well as flying-fish larvae. Our last two sites had an amazing amount of diverse larvae from families like Bothidae, Carangidae, and Synodontidae. We are hoping this exciting trend continues!
One of the important, sometimes overlooked, aspects of any expedition is the hard work of the field researchers that help to collect the enormous amount of specimens and data. Today's post is about recognizing the folks out here keeping the wheels turning.
PhD Student Larissa Kitchens
Graduate Technician Carlos Ruiz
Undergraduate Technician Chris Steffen
Undergraduate Technician Josh Bowling
Undergraduate Volunteer Jason Williams
Without these students and technicians putting forth their best efforts and working together as a team, these projects would run far less smoothly.
Tomorrow we hit the last leg of our journey, Stations 37-48, followed by our trip back to Port Fourchon. It's been fantastic so far but there is still a good deal of sampling left to do, so stay tuned!
Blog posted for Jeff Plumlee:
Howdy from the Blazing Seven!
Today was another rousing success with an early 500-m midwater trawl at 04:00 followed by our 13th station at N 27 W 89 36' at 06:00. Our midwater trawl consisted of shrimp, squid, jellyfish, and of course, lanternfishes (Myctophidae). It was another beautiful day with clear blue water, a gentle breeze, and 1 - 2 foot seas. We progressed through twelve stations today and continued to have Sargassum at every one. However, with Sargassum, comes abundant diversity, including filefishes (Monacanthidae), triggerfishes (Balistidae), Sargassum fish (Antennariidae), flyingfishes (Exocoetidae), dolphifishes (Coryphaenidae) and others, along with shrimp and crabs. We also found several billfish and flyingfish larvae as well in our neuston and bongo nets.
juvenile flying fish
One of our primary objectives on this cruise is to collect ichthyoplankton, primarily billfishes of the families Istiophoridae and Xiphiidae, tunas of the family Scombridae, dolphinfishes (Coryphaenidae) and flyingfishes (Exocoetidae). Dr. Jay Rooker from Texas A&M University at Galveston and many of his students utilize larvae and samples collected from these trips to create a better understanding of these pelagic fishes. Through the utilization of techniques such as otolith chemistry and genetics, along with the collection of oceanographic parameters, researchers can understand in detail the life history of these fishes as well as habitat preference, spawning locations, and population structure. Continued quantitative sampling using multiple gear types, with replicated sampling, allows detailed analysis over seasons and years, revealing long-term trends which are crucial to understanding pelagic ecosystem patterns.
Tonight we are making the trip from N 27 to N28 to begin our second leg of the trip, the westward transect back towards Port Fourchon. We have finished our last midwater trawl so sampling begins tomorrow at 06:00 with neuston and bongo net tows, so stay tuned for more updates!
Blog post from Jeff Plumlee on the Blazing Seven:
Howdy from the Blazing Seven!
We have had an incredibly productive day! This morning we woke up at 0300 as we arrived on our first site at N 27 W 91. Shortly after, we completed our first 500m mid-water tow with a ring net. In the tow we collected several deepwater species including, lanternfish (Myctophidae), deepwater shrimp, and various fish larvae. After the 500m tow we rested and prepared till 0600 to start our first site for neuston and 100-m bongo nets tows looking for billfish and tuna larvae. The most abundant feature of today was Sargassum, and there was plenty of it, a pattern we are very familiar with in Galveston, Texas. However even with the Sargassum we were able to find plenty of jacks (Carangidae), f ilefish (Monacanthidae), and a good number of flyingfish larvae, among other pelagic species. Despite the potential setbacks Sargassum can cause, we were able to complete 12 sites from N 27 W 91 to N 27 W 89.5 which, according to Captain Thomas, is a TAMUG Billfish cruise record for site sampling productivity, WHOOP!
In addition to towing nets, we also filtered water at several select stations to help aid fellow researchers at TAMUG. Dr. David Wells of Texas A&M at Galveston, and his soon-to-be PhD student, Travis Richards, are focusing their efforts as apart of the DEEPEND Consortium on pelagic organisms and their trophic connectivity. One way that this can be accomplished is through stable isotope analysis. Looking at the ratio of heavy isotopes (Carbon 13 and Nitrogen 15) can help researchers understand the contributions to an organisms' diet. Specifically, contributions from primary production (using Carbon 13), and trophic position (using Nitrogen 15). Gathering the contributors of the base of the trophic web as well as the estimates of their associated locations and oceanographic features is crucial to applying effective models to the system. That's where we come in. Filtering water and analyzing the phytoplankton collected in the filter, along with collecting vegetation from the site (like Sargassum) is an easy way to create these regional maps and is crucial to understand food web dynamics.
Tonight we will complete our second 500-m mid-water tow, and tomorrow we hope to finish our N 27 transect as well as a third 500-m mid-water tow. We are continuing to run into new and dynamic oceanographic features, so stay tuned for updates!
After a few delays and a change in available crew, the Blazing Seven is back in action! I am unfortunately not out there with them, but I will be posting blogs and updates on the cruise tracker for them. Jeff Plumlee, a researcher from Texas A&M Galveston, will be sending us updates from sea. Unfortunately, they will not be able to send pictures or videos during the cruise, but we will post some in our picture gallery after they get back. Here is the first blog from the Blazing Seven!
Jeff Plumlee, Shark Biology and Fisheries Science Lab, Texas A&M Galveston
Howdy from the Blazing Seven!
This morning, at approximately 0700 hours, The Blazing Seven left from Port Fourchon, LA with six Texas A&M at Galveston student researchers, and four Blazing Seven crew members, to begin our first Ichthyoplankton cruise looking for billfish and other pelagic fish larvae. This research team is conducting this survey as part of the GOMRI initiative as members of the DEEPEND Consortium to study pelagic fish ecology and trophic connectivity. This is our second attempt at the cruise after being stalled on June 1st due to a mechanical malfunction, but after some repairs, we're back! Today was designated primarily as a travel day, as it will take us about 20 hours to arrive at our first site, but we were still able to start collecting data.
Dr. Kevin Boswell and his Research Technician Adam Zenone, of Florida International University, have equipped the Blazing Seven with three separate SONAR transducers that they will use to monitor the DSL (deep scattering layer). The DSL is a layer of fish and zooplankton that gather at between 300 and 500 m depth during the day, and within the top 200 m at night. This mass aggregation of fishes can cause an anomaly in SONAR estimates of depth, due to the sound bouncing off of the many fishes' swim bladders, and represents a very large amount of biomass in the open ocean. Dr. Boswell will use the information gathered on the cruise to observe the intricacies of the DSL, as well as the diel vertical migration of fishes and zooplankton, and use these techniques to better understand the ecology of deepwater ecosystems.
Today we were able to deploy these three transducers as well as calibrate them for our six-day cruise throughout the Gulf collecting several cycles of the movement of the DSL. We also were able to get our first glimpse of pelagic fishes! Jacks, Tuna, Mahi, and Flying Fish galore, along with a very curious Silky Shark that was attracted to the calibration device we used for the SONAR transducers.
Tomorrow morning we start very early with our first nighttime deep water tow using a ring net at 500m. So make sure to stay tuned for what we find!
Hello, everyone! Report from the Education-Outreach Team on our first Teacher-at-Sea, Carol Gordy, preparing for the DEEPEND Ichthyoplankton Cruise heading out in a couple of days. Carol joins our team from Sunlake High School in Pasco County, Fl where she teaches marine science classes. She has been teaching for 25 years and will be sharing her experience at sea with us through her daily blog posts. Follow her journey and ask lots of questions! Check out the DEEPEND main page and news for more details about this cruise and it's role in the DEEPEND program- safe travels, Carol!
Heteropod snails by Mike Vecchione
I am out here on the R/V Point Sur primarily to study cephalopods, the squids, octopods and their relatives. However, I have decided to write about a different group of very interesting animals. The swimming snails called heteropods are a group about which most people know nothing and nobody knows much. They are not closely related to the other, and somewhat better known, group of snails that spend their entire lives in the pelagic environment, the pteropods.
Heteropods are active visual predators and, although most are small (planktonic), some can get quite large -- up to a half meter in length. I studied them many years ago and am now becoming reacquainted because we have been catching them regularly in our samples from the upper water layers. Three families exist, which seem to show a progression of evolution into pelagic life. Animals in the family with the smallest animals but most species have a coiled transparent shell into which they can withdraw their body and seal it off with a standard snail trap door, called an operculum. The shell has a keel on it, similar to what you might see on the bottom of a sailboat. The second family gets much larger but still has a keeled shell; for most species in this family the shell covers the guts like a hat. The third family loses the shell during transformation from the larval stage. They are streamlined and can swim quite fast. They should definitely be considered nekton rather than zooplankton.
All heteropods have well developed, but peculiar, eyes. They have a narrow retina that the can rotate up and down. They probably form an image much the same way that the image forms on a TV screen, aggregating one line after another rather than the whole picture forming at once. Another characteristic of all heteropods is a single fin on the belly. They normally swim by undulating this fin. Additionally, the larger species can swim in rapid bursts by eel-like undulation of the entire body, which is shaped somewhat like a fish including a flattened tail. The bodies, especially in the larger species, are remarkably transparent except for the eyes (which have to catch light), the guts, and the organs of the mouth. Often when we are sorting our catch, the only way you can tell that there is a large heteropod is by the eyes, guts, and mouth.
The mouth, located at the end of a trunk-like proboscis, has a structure characteristic of snails and most other molluscs, a tooth-covered tongue called a radula. This is used to grab and tear the heteropod's prey. The proboscis is why these animals are sometimes called "sea elephants". What they eat varies among the three families. The small species in the fully shelled family eat other snails, especially pteropods. They have a sucker at the base of the fin and use it to hold the shell of their prey. Not much is known about the natural prey of the other two families. It has been proposed that they eat a variety of prey, ranging from jellyfish to arrow worms, perhaps even including small fishes. Incidentally, the sucker is reduced in the other families and seems to be used to hold a sexual pair together during mating, so that the male can transfer a packet of sperm (spermatophore) to the female.
We are finding that these active predatory snails are quite common out here, It will be interesting to figure out their importance in the pelagic ecosystem of the open Gulf of Mexico.
Carinaria lamarcki is an example of heteropod from the family Carinariidae (top image).
A close-up of the shell of Carinaria lamarcki
An example from the another family of heteropod - the Pterotracheidae. This is Pterotrachea coronata.
An example of the heteropod family Atlantidae. This is Oxygyrus inflatus.
For more imformation, see http://tolweb.org/Pterotracheoidea/27801
Seed shrimp are crustaceans (related to shrimp, crabs, and lobsters). They belong to a group known as ostracods. There are roughly 8,000 extant (living) species. Ostracods have five paired appendages on their heads and one to three pairs of appendages on their bodies. Another common name for the group is “mussel shrimp” because they have a two part, hinged shell (known as a carapace) that envelopes their bodies…like a clam or a mussel.
Giant ostracods, Gigantocypris sp., are deep water seed shrimp. Members of this genus appear to be among the largest of ostracods on earth, reaching a total size of 32mm diameter. This one was the size of a green pea. The eyes of these crustaceans (“nauplius eyes”) are divided into two lobes and have reflectors built in. The eyes can detect bioluminescence from potential prey items, such as is produced by copepods. Prey items include copepods, mysids, chaetognaths, medusae and other small invertebrates – even very small fish. Gigantocypris store their eggs internally, in a brood pouch. The eggs develop there until they hatch (as miniatures of the adults). Juveniles are released into the pelagic environment. This individual is brooding purple eggs inside its carapace. Populations that have been studied are biased with 3 to 6 times more females than males. Roughly five species have been described inhabiting all of the world’s major oceans.