Friday, July 19, 2019

The Solar-Powered Sea-Slug

P. ocellatus found during our dive. Credit: 

HIMB/L. Noonan
While snorkeling off the sandbars of Moku O Loe I took a pause to defog my mask, giving a fellow intern (Rachel), the opportunity to take a moment and smell the seagrass. While waiting, she discovered a small patch of sand moving across the algae as if it were late to its walking tour. She then noticed two little stalk-like projections from the moving cluster of coral remains and discovered it was not sand at all.

These little projections are called rhinophores which are typically used for chemoreception and rheoreception. Chemosensing is when organisms can determine the presence of certain chemicals so it’s similar to our sense of smell. Rheoreception is the ability to sense the direction of the currents. The organism to which these rhinophores are attached: Plakobranchus ocellatus, or more commonly known as the ringed sap-sucking slug. They have several rings distributed amongst their body which range from blue to green to yellow, hence the term “ring” in the name. There are two black dots located between the two rhinophores which contain ocelli. These ocelli are simple photoreceptors, meaning the slugs primarily use them to detect movement in the environment around them.

A. Arrow pointing to parapodia. B. Arrow pointing to
rhinophores C. Arrow pointing to ocelli. D. Parapodia
spread, revealing the green lamellae. Red arrow
points to the stomach. E. The underside.
Credit: Zookeys/M. A. Munoz
Well what about the rest of the name? What is sap-sucking? The raddest function of this slug is that it has the ability to extract and use chloroplasts from algae that it has ingested (functional kleptoplasts). This potential kleptoplasty classifies this gastropod as a mixotroph, which is an organism that is capable of phototrophy and heterotrophy. According to an article published in 2012 by Maeda & Hirose et. al., photosynthesis is a mechanism that commonly only occurs in starved sap-sucking slugs. Their primary source of nutrition stems from the consummation and digestion of algae, which concurrently provides them with fresh kleptoplasts. These kleptoplasts are usually visible within the lamellae (gills) when the parapodia of the slug has been spread.

                Kleptoplasty. An eyeful upon approach, but quite easy to remember when you break it down. Klepto is a term that has been derived from the term kleptomaniac. A person who is a kleptomaniac is someone who constantly has an urge to steal. When you add klepto- to the term -plasts (chloroplasts) you get an organism who steals the chloroplasts from others (in this case algae). Similarly, cnidae (stinging cells contained by cnidarians) that are ingested by a nudibranch would be termed kleptocnidae.

With all the new knowledge you have you’re probably wondering where you can find them. These little gastropods of the phylum mollusca are typically found in the indo-pacific and are comfortable in sandy and silty reef areas. However, these slugs can still reach depths of down to 50 ft (Hoover 2007).

These gastropods are hermaphroditic and have a spiral cream-colored eggs sac that holds the young. These sacs have reportedly been found on algae and on a species of sea cucumber that is commonly found here in Kaneohe Bay. This commensal association with the sea cucumber species Holothuria atra which is the black sea cucumber you usually find in the touch tanks. An experiment done by Mercier and Hammel in 2005 discovered that P. ocellatus favor H. atra because of the sea cucumbers ability to produce a toxin that deters possible predators of P. ocellatus. This allows the gastropods spawn under protection.

Ring details of P. ocellatus. Credit: The University
of Queensland Australia/W. L. Hong, 2011.

On the topic of protection, P. ocellatus also produces a mucus that duals as a camouflage cover and as a means of locomotion. The mucus is secreted over the parapodia which adheres sediment to their dorsal side, allowing them to blend in with their environment. The mucus is similarly secreted ventrally, where they are able to smoothly glide over it and move safely without harming their epidermis.

 Now that you’ve been SUCKED in by these little sap-sucking slugs I encourage you to come out to Moku O Loe and explore the reefs. We have a variety of other unique invertebrates that are pleasant to observe... and who knows, maybe you’ll find one we’ve never encountered!




Hoover J. P. 2007. Hawaii’s Sea Creatures: A Guide to Hawaii’s 
Marine Invertebrates, Revised Edition.

Maeda T., Hirose E., Chikaraishi Y., Kawato M., Takishita K., 
Yoshida T., Verbruggen H., Tanaka J., Shimamura S., Takaki 
Y., Tsuchiya M., Iwai K., Maruyama T. 2012. Algivore or 
Phototroph? Plakobranchus ocellatus (Gastropoda) 
Continuously Acquires Kleptoplasts and Nutrition from 
Multiple Algal Species in Nature. Vol. 7 Iss. 7. Accessed July 
10, 2019.

Mercier A., Hamel J. 2005. Note on the association between 
Plakobranchus ocellatus (Mollusca: Gastropoda: 
Opisthobranchia) and Holothuria atra (Echinodermata: 
Holothuroidea). Cah. Biol. 46 : 399-402. Accessed July 11, 

Munoz M. A., Velde G., Meij S., Stoffels B., Alen T., Tuti Y., 
Hoeksema B. 2016. The phylogenetic position of a new 
species of plakobranchus from West Papua, Indonesia 
(Mollusca, Opisthobranchia, Sacoglossa). ZooKeys 594: 73-
98. Accessed July 12, 2019.

Friday, July 12, 2019

The White-Spotted Pufferfish

Pufferfish hiding in sediment, seen near
bottom of the photo. Credit: HIMB/R. Nunley
On our snorkel adventure this past week, LiAn and I came across what looked like to be a moving rock. As we got closer, we noticed it had eyes and fins. We then realized it wasn’t a rock at all and that it was a small pufferfish.

This pufferfish you see hiding in the sediment to the right is called a white-spotted pufferfish (Arothron hispidus). The spots may be hard to see which is why they are also commonly called the Stripebelly Puffer. Its Hawaiian name, O’opu hue means stomach like a gourd (Titcomb, 1972). O’opu hue is a great name for pufferfish because they are known to expand their stomachs with water and form a gourd shape with their bodies. They do very well hiding on the seafloor. As you can see in the picture, they are covered in sand and camouflage with the floor beneath them making it almost impossible to see at first glance.

Stripebelly puffer. Credit: Keoki Stender
The white-spotted puffer belongs to the family Tetraodontidae. The name Tetraodontidae comes from a chemical that many pufferfish have in their body called tetrodotoxin. It can be found in many marine animals including porcupine fish, triggerfish, and sunfish. It can be found in organisms living on land too. For example, the rough-skinned newt, Taricha granulosa has tetrodotoxin in their skin, ovaries, and in their muscles as well. Some predators of the rough-skinned newt, such as the garter snake (Thamnophis spp.) has a resistance to this toxin in order to continue preying on the newt (Mebs et al, 2019). The bacteria living in these animals create this neurotoxin making the pufferfish and newt poisonous to most predators, including humans (Bragadeeswaran et al, 2010). Tetrodotoxin is found mainly in the puffers skin and in little sacs throughout the body. A human has to ingest only a few milligrams of tetrodotoxin for it to be deadly (Bragadeeswaran et al, 2010). This toxin is not their only defense mechanism though. Like all puffers, the white-spotted puffer inflates and can blow up like a balloon if threatened. They do this by sucking in a lot of water quickly and expanding their stomach to become a spherical shape. This confuses predators and makes them much more difficult to consume. This can be dangerous for the pufferfish because stretching out their stomach and skin constantly makes it much more difficult to swim around. Once they are blown up, they can only float around in the water until they return to their normal size. With all of the self-defences the puffer has, it doesn’t use all of them at once. First, the pufferfish will blend in with the sediment or rocks below and camouflage itself to the best of its ability in hopes of not being seen. If the puffer is unsuccessful in hiding and gets spotted by a potential predator, the puffer will then puff up and hope that the predator is too lazy to try and figure out how to fit it in its mouth. If puffing up into a big ball doesn’t work, the puffer will take one for the team and hopefully kill or harm the predator with the toxins as it’s getting consumed.
Jaw and teeth of the closely related
spiny pufferfish. Credit: HIMB/R. Nunley

The white-spotted puffer feeds on algae, mollusks, sponges, corals, crabs, sea stars, and sea urchins (Randall, 2005). The pictures you see to the right are pictures of a pufferfish jaw. As you can see, all of their teeth are fused together to form a single plate. This beak-like jaw helps the pufferfish grind and crush its prey. This is why puffers are able to eat corals, mollusks, and sea urchins. Its diet includes organisms with tough outer shells or skeletons and by having this jaw shape and type, they are able to feed on what they like best.

You will most likely find the white-spotted puffer around the Hawaiian islands, Indo-Pacific, and French Polynesia. We found this white-spotted puffer on the south-west edge of Moku o Lo’e about 4-5 feet deep. They are very common in Hawaii and Kane’ohe Bay. These pufferfish may look cute and fun to play with, but they can easily bite off a finger, so admire their beauty from a respectful distance.

- Rachel

Bragadeeswaran, S, Therasa, D, Prabhu, K, & Kathiresan, K. (2010). Biomedical and pharmacological potential of tetrodotoxin-producing bacteria isolated from marine pufferfish Arothron hispidus. Journal of Venomous Animals and Toxins including Tropical Diseases.
Mebs, D., Yotsu-Yamashita, M., & Toennes, S. W. (2019). Tetrodotoxin content of Rough-skinned Newts, Taricha granulosa (Salamandridae), from their northern distribution range, British Columbia, Canada, and Southeast-Alaska, USA. Salamandra
Randall, J. E. (2005). Reef and Shore Fishes of the South Pacific: New Caledonia to Tahiti and the Pitcairn Islands. China: Library of Congress Cataloging-in-Publication Data. 
Stender, K. (n.d.). Stripebelly Puffer, Arothron hispidus: Fish Hole, Midway Atoll, 40 feet [image].
Titocomb, M. (1972). Native Use of Fish in Hawaii. Honolulu: The University Press of Hawaii.

Monday, November 26, 2018

Giant Snails: The Hawaiian Tiger Cowry

            If you have ever been to the observation tanks at the Hawaii Institute of Marine Biology, you may have noticed the large ovoid shells along the walls or hiding under the coral heads.  These majestic creatures are Tiger cowries, Cypraea tigris.1 a large sea snail under the phylum of Mollusca, and over the past two years I have been using them as model organisms to examine the palatability and chemical defenses of sponges found throughout Kaneohe bay.  Yes, these snails are actually nocturnal predators that feed on sponges, very frequently found eating the invasive orange keyhole sponge, Mycale grandis, and they are quite peculiar organisms.

            Tiger cowries fall under the class Gastropoda, translating to head-foot, and although that pink region may look like a mouth, it’s actually its foot!.  As a matter of fact, their mouth can be found in the fleshy cavity between the two antennae that are the main sensory organ used for detecting food by smell and touch.  Tiger cowry mouths consist of a fleshy orifice called a proboscis, containing a scraping conveyor belt structure, a radula, which scrapes off sponge tissue that feeds into its digestive tract.  The spore-like whiskers that look like frosted dreads of the cowry are called papillae, and they are apart of the mantle. The mantle are two tissue layers that secrete calcium carbonate crystals to create, repair, and maintain its finely polished shell.

Tiger Cowry with Brown Mantle
Tiger Cowry with Green Mantle
          Tiger cowry shells can range from white to black, but are usually white, yellowish, or light blue green, with dark brown to black spots. Some researchers postulate that the patterns found on the tiger cowrie shells are determined by the patterns found on the mantle while other research has found a correlation between the density of spot pigments with shell size, as a shell grows larger, the dark spots are spread out, the space between being white.2 Although one could be fascinated by the beautiful design of these shells, I want to draw attention to its size.  Not only are they the largest cowries I have observed throughout Hawaii, but I have come to find that Hawaiian tiger cowries are not like other cowries found throughout the rest of the world.

          Tiger cowries can be found throughout the Indo-Pacific Ocean, off the coasts of Japan, Singapore, Australia, Polynesia, and Hawaii.  Although the average shell size of tiger cowries ranges from 6-9 cm, the average size of Hawaiian tiger cowries is 11-12 cm, the largest size observed size is 16 cm.  This size discrepancy is one of the main features that This is incredibly peculiar, as the environmental or physiological pressures in Hawaii that would influence the size of these cowries to increase.  Could it possibly be due to lack of predators and an abundance of food driving?  Tiger cowries in Hawaii illustrate a 50% size increase from their Indo-pacific counterparts, so would this be considered as tropical, or even endemic, gigantism? One may even hypothesize that the tiger cowries found in Hawaii have significant genetic differences from their Indo-Pacific counterparts that they could be classified as a subspecies C. tigris schilderiana.3
Left = Hawaiian Tiger Cowrie (11cm length)
Right = Tiger Cowrie from Indo-Pacific (7 cm length)

-Andrew Osberg

  1. Linnaeus, C. Systema naturae per regna tria naturae: secundum classes, odines, genera, species, cum characteribus, differentiis, synonymis, locis. 10th edition ed. Stockholm: Laurentius Salvius
  2. Reid, C.E. Comparison of shell pigmentation and size in Cypraea tigris.  Accessed: November 26, 2018.
  3. MolluscaBase (2018). Cypraea tigris schilderiana C. N. Cate, 1961. Accessed through: World Register of Marine Species at: on 2018-11-26

Thursday, October 25, 2018

NOAA OE Teachers Workshop

Aloha Everyone,
    This past weekend the Community Education Program hosted our 10th annual NOAA OE Teachers Workshop here at the Hawai‘i Institute of Marine Biology. We had 16 visiting educators join us Saturday October 13, in the Makers Lab.
     Kicking us off with on mysterious depths of the ocean, Mark Heckman explained "why we explore" and the significance of methane hydrates. He guided us through “Exploring the Deep Ocean with NOAA”with a hands-on module where teachers create methane hydrate models with toothpicks and candy. Pictured is the a activity of the successfully created models!

      CEP Educator Andrew Osberg guided teachers  through “Invent a Robot."  ROVs are essential in deep ocean exploration for gathering high quality imagery and samples.  Teams were able to build their engineering design skills and by fashioning innovative ROV arms that could successfully pick up a cup of water, using only scratch cardboard pieces.  These teams also compared the efficiency between hydraulic and pneumatic systems.
     We also had the privilege of having guest lecturer Joyce Miller, the 'Queen of Multi-beam' unravel her work with multi-beam technology from several research vessels.
Image from:


     The group wrapped up with water column investigations on the Oceanographic Yo-Yos which introduced teachers to the CTD module. A CTD is water column exploration technology that includes a package of electronic devices that measure conductivity, temperature, depth and collect water samples. With simple tools like pH strips, thermometers and vinegar, students are able to recreate open ocean research in a classroom.
     There are many more lesson plans and our educators got to go home with the educator goodie bags! Join the Oceania for opportunities such as this. We hope to see you next time!

Thursday, August 30, 2018

See you soon!

Aloha Everyone! 💥

Today is my last day here at HIMB for my internship this summer, as I will make my way back to Massachusetts and Smith College. I have had a fantastic time here over the past few months, and I am so grateful to have had the opportunity to be a part of our CEP team. Over my time here, I have met many wonderful people who have always been so caring, friendly and inviting to someone far from home like me! I have had the opportunity to run and help with many tours, labs, and an overnight, as well as work on a few different projects, such as creating new signage for our touch tanks and new cue cards for our walking tours. Just the other day I created a worksheet for our labs and classes that will be put into use soon. I have been out almost every day cleaning the touch tanks, one of my favorite activities here since I get to spend time with some of our lovely creatures. Overall, this has been a wonderful experience that I will look back on and cherish. But I won't be gone too long, as I plan on coming to visit this winter, and perhaps running some more tours then!

See you soon,

Ginny Svec 😄
CEP Intern

Wednesday, August 29, 2018

Pacific Portuguese Man-of-War

Aloha everyone!

On a three-day-program with students from Beijing this past month, much of the Community Education Program team was snorkeling on the sand bar, when I had to bring one cold student back to our boat. On my way back to the other snorkelers, I got caught in the long tentacle of a Pacific Portuguese Man-of-War (Physalia utriculus /pa'imalau)!

A Pacific Portuguese Man-of-War swimming in Hawaiian waters.
Its float and some of its medusae are visible,
with the longer fishing tentacle drifting further below the picture.
Photo by
Pacific Portuguese Men-of-War, otherwise known as bluebottles, belong to the phylum Cnidaria, meaning that they have a stomach and mouth, radially symmetric curved bodies which open at one end, and tentacles covered in stingers or nematocysts. These nematocysts help cnidarians to be able to eat and protect themselves. A cnidarian can either be in the form of a polyp or a medusa, where the polyp is attached to a surface with its mouth pointing upwards (i.e. an anemone or a coral) and the medusa form faces down and is free-swimming (i.e. a jellyfish). A Man-of-War is in the medusa form of a cnidarian since it faces downwards as shown on the right.

Though many people refer to these gelatinous creatures as jellyfish, they actually belong to the class Hydrozoa, unlike true jellyfishes which are as scyphozoans and cubozoans. Hydrozoa create their medusae through budding, or asexual reproduction through the creation and cleavage of a clone on the hydrozoan. Syphozoa on the other hand, use strobillation, or the spontaneous segmentation of  their bodies to be able to create their medusae, while Cubozoa polyps metamorphose to become medusae.

The Pacific Portuguese Man-of-War belongs to the order Siphonophora within the class Hydrozoa. Typically, these open-water or pelagic animals use their floats (the puffy-looking polyp above the tentacles and medusae) in order to rise and sink in the water column. They can do this by altering the amount of gas or oil within their floats, or by swimming. Unlike other hydrozoans, the Man-of-War stays at the surface, using its carbon monoxide-filled float to keep it above the water, with a crest to help it move with the wind. Though cnidarians can be either solitary or colonial, and the Man-of-War may look like one solitary animal such as a jellyfish, they are actually made up of many medusae and polyps, which bud from the original polyp (the float) as mentioned above, and attach to it to form a colony. The medusae hanging below the float can also help with propulsion through the water, and each perform specialized tasks such as digestion, fishing, and sexual reproduction via eggs and sperm. A single tentacle extends down into the water column, paralyzing or killing its prey before contracting to feed itself. Check out how these animals move in the videos linked below:

An image of a Man-of-War's float with its
long tentacles trailing behind it.
Photo by Arina Habich.
A picture of me after I got stung. You may be able to
see the red mark from the right side of my mouth across 
my upper lip, and up to where I am pointing on my cheek.
The tentacle got caught around my snorkeling mask!
Photo by me.

Since these creatures are a dark blue or even purple color, they are difficult to spot in the water, until it is too late. Your best chance of seeing one before it stings you is by looking for its float above the surface of the water. If you do happen to get stung, however, recent research by UH suggests that vinegar works well at stopping cnidae discharge which causes the stinging. Other methods of stopping stinging such as alcohols, urine, shaving cream and baking soda actually caused cnidae discharge and did not stop it from happening. This means that these methods which were previously thought to be a better method for stopping Man-of-War stings do not seem to help at all, and may actually harm you more!

After being stung, the burning for me personally lasted about an hour until it was completely gone. However, I had been touching it before I knew not to do that, and instead to rinse with salt water and vinegar. Some people and sources seem to suggest that this feeling will only last for about 20 minutes, while others say that they had pain and red marks in those areas for about a week! I suppose that everyone's pain tolerance is different, and some people may have sensitive skin or allergies as well. For me, though, the pain just felt like a very bad razor burn.

An image showing the relative size of a Pacific Portuguese Man-of-War compared to a person's foot. That thin tentacle is what wrapped around my snorkeling goggles, stinging me across the face. Even though these creatures are fairly small compared to us, their sting sure packs a punch!
Photo by

Fortunately I got stung by the Pacific Portuguese Man-of-War, which can have a float of about 1 to 2 inches in length and a long tentacle below, instead of the Atlantic version which can have a float up to a foot long, with many fishing tentacles up to 30 feet long! Though I was the only person to get stung out of our snorkeling group, some of our other staff members noticed a cloud of Men-of-War floating towards the school group on their way back to the boat after I had been stung, since it was such a windy day. It looks like this intern took one for the team!

Mahalo nui,

Ginny Svec
Our group of students snorkeling with one of our CEP staff members, Kyla. A short distance away was where all of the Men-of-War were swimming.
Photo by Leon Weaver.

Bouillon, Jean, et al. An Introduction to Hydrozoa. Publications Scientifiques Du Muséum, 2006.

Hoover, John P. Hawai'i's Sea Creatures: a Guide to Hawai'i's Marine Invertebrates. Mutual Pub., 1999.

Wilcox, Christie L., et al. “Assessing the Efficacy of First-Aid Measures in Physalia Sp. Envenomation, Using Solution- and Blood Agarose-Based Models.” MDPI, Multidisciplinary Digital Publishing Institute, 26 Apr. 2017.

Friday, July 13, 2018

New Website


A new website has recently been created for HIMB. There, you can find resources needed to learn more about us, such as our contact information, the various visiting programs that we offer as well as their costs, and more. This site is still being updated and more from the old website will be available soon, so make sure to be on the lookout for updates. This blog will still be maintained, and there is even a link for it on the new website! Click here to visit our new site.

Moku o Lo'e from a bird's-eye view. Images from HIMB blog.
Mahalo nui!