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By Dante Fenolio

Sea cucumbers are echinoderms – related to starfishes and sea urchins.  Sea cucumbers have an interesting body plan that includes something known as a “respiratory tree.”  The respiratory trees are highly branched systems (two per animal on either side of the sea cucumber) that take water in and out through a cloacal pore.  The flow of water is used in respiration.  Now consider the “pearlfish.”  These fishes are a moderately diverse assemblage – but they have one thing in common… they inhabit the digestive tract of sea cucumbers.  They use the water flow going in and out of the sea cucumber to locate the cloaca… then they swim right in.  Often times these fishes live alone but sometimes, a pair will live together within the same sea cucumber.  One group of pearlfishes harm their host by consuming their gonads and other internal organs – a truly parasitic relationship.  But with the rest of the pearlfishes, the fishes do not do any harm while the sea cucumber serves as a home base. 

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Pearlfish collected on DP08 in the Gulf of Mexico (Photo:  D. Fenolio)

The "Tongue Eating Isopods" are a group of isopod crustaceans that inhabit the mouths of fishes as adults. This "Tongue Eater" is of the family Cymothoidae and is of the genus Cymothoa. Ispods of this genus all start life as males. If they are lucky enough to find their way into the mouth of a fish (lots of larvae in the water column - perhaps larvae grab onto small fish and move into a larger fish when the small one is eaten?). Once they do get into the mouth of a fish, they latch onto the tongue with sharp grasping legs. They tighten their grip of the tongue and cut circulation. Ultimately, the tongue rots away except for a stub at the floor of the mouth. The isopod will spend the rest of its life living in the space where the tongue of the fish was and holding onto the "tongue stub." Presumably, the isopod helps itself to bits and pieces of food as the fish eats. We found this individual within the remains of a large flying fish that was itself in the gut of a Mahi Mahi (Coryphaena hippurus). We assume the isopod had replaced the tongue of the flying fish. The dorsal aspect is to the left, the ventral aspect to the right. If you look under the ventral aspect, you can see a pouch (a "marsupium") where this female had been brooding a clutch of developing young. All of these isopods start life as males. If they find a fish host and replace the tongue, they change to the female sex. Newly arrived males to a fish mouth will mate with the resident female - yes, in the mouth of the host fish or on the gill arches. Males typically inhabit the gill arches of the fish. Some sources argue that all isopods enter the fish through the gills, not the mouth. Observed on the Gulf of Mexico, July 2022 during DEEPEND-RESTORE work.

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Tongue eating isopod collected from DP08 in the Gulf of Mexico (Photo: D. Fenolio)

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 Hi!

My name is Hannah Johnson and I am currently pursuing my Master’s of Science degree in Marine Science under Dr. Tracey Sutton at Nova Southeastern University. I am lucky enough to attend my first DEEPEND/RESTORE cruise on R/V Point Sur this year. While the focus of my thesis project relates to the reproductive habits of the deep sea fish genus Chiasmodon (Scombriformes; Chiasmondontidae), my predominant purpose on this cruise is to help record the collection of all the deep sea fauna we find.  

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The MOC coming onboard from a night tow (Photo: H. Johnson)

I work with Dr. Rosanna Milligan and April Cook to weigh, measure, and preserve each specimen.  We log the specimens into the database to be able to document various notes, along with the measurements, site collection, and much more.

It is extremely important that we ensure each speciment gets preserved properly as many scientists and students will use our specimens for projects, even years later.  For example, the fish genus Chiasmodon I work with was caught and documents 10 years ago!  Thanks to great preservation techniques, I am able to do kinds of analyses with their reproductive tract as well as gut and diet analysis by my colleague Travis Kirk.

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We were able to catch a Chiasmodon sp. with a full stomach!

 It has been an amazing experience to see first-hand what goes on during the DEEPEND cruises. It helps to give insight into how the lab specimens from years ago were collected.

Thanks for reading!

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By Lisa Rose-Mann

Hi! I’m having a great time on my first research cruise. Having worked with samples from previous cruises I have longed to be able to join the DEEPEND crew. I really wanted to see the MOCNESS in action!  This is a net system that opens and closes at different depths (for this cruise, 0-1500 m down).  The diversity of life we are finding is amazing and I’m completely blown away by the cool deep sea creatures and their adaptations I’ve been able to see firsthand.

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From left to right:  Loosejaw, hatchetfish, viperfish, black dragonfish (photo: L. Rose-Mann)

My current research is performing chemical analysis on the tissues of squid and their predators for signs of contaminants from things like oil spills, pesticides, plastics and other persistent organic pollutants. As part of this crew I am collecting samples to bring back to the lab for that purpose.

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Lisa processing a sample onboard (Photo:  H. Judkins)

I’ve eaten really well on board, seen a lot of cool birds, taken my shot a Mahi Mahi (haven’t caught my own yet, but there’s still time) and learned a ton about these animals so far. Additionally, having this kind of time with some really amazing scientists and been very rewarding.  I’m beyond thrilled to have had this opportunity and hope to find a way join the crew again in the future.

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Our first stop!

This area is a deep water coral reef on the upper continental slope dominated by Lophilia species (a deep sea coral).  We explored this area briefly last year to investigate interactions between the deep scattering layer and the benthic community.  This year, we are visiting this site twice to continue exploration with our first MOC deployment and retrieval happening last night.

This is our most shallow site with a bottom depth of 450 m and we towed the MOC10 downslope heading deeper to a depth of 402 m as to not disturb any benthic communities.  This was a night trawl so we expected many deeper-living animals coming to the epipelagic zone (0-200 m) as there is a nightly vertical migration of animals towards the surface to feed under the cover of darkness.

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T. Frank and H. Judkins emptying the cod ends into buckets for lab sorting (Photo: L. Rose-Mann)

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J. Moore, T. Sutton, T. Frank, H. Bracken-Grissom sorting species (Photo:  L. Rose-Mann)

Once the cod ends were collected and sorted by the taxonomists, identifications were made of the various faunal groups (fishes, cephalopods, crustaceans). Highlights included our usual suspects such as eel larvae, a pseudo-oceanic hatchetfish species which is common in this habitat, Sergia hans jacobi (crustacean species), pteropods, and heteropods as well as some unexpected finds like a Star Eater fish and a snake-eel larvae that doesn’t match any known species at this time.  Exciting stuff!

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J. Moore holding an example of an eel larvae he identifies in the field (Photo: H. Judkins)

We are now off to deeper waters of the Gulf of Mexico for our next deployment- stay tuned!

Heather J.

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Yeehaw!  Almost time to shove off on our next DEEPEND/RESTORE cruise which will set sail tonight just after midnight on the R/V Point Sur.  The team is busy stowing gear, repairing holes in nets, and making sure we have everything we need for the next 12 days.  We will be deploying the MOCNESS net system as we have on past cruises and will be getting to out our first station tomorrow afternoon.  We will be posting blogs throughout our journey so stay tuned!

Cheers- Heather J

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R/V Point Sur, docked in Gulfport, MS (photo: L. Rose-Mann)

 

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