Tag Archives: Big Island

Giant Aliens of Kona

Okay, so they aren’t aliens.  They are actually giant fish- Manta Rays to be exact-and when people visit us in Kona one of their top priorities is to see these rays.  It’s a breathtaking show of tumbling, spinning, and, well, eating really.  It has been described as an underwater Vegas show which is spot on.  However,  in this version the showgirls are trying to put on the pounds!  There are lights shining everywhere and constant action, there’s so much going on that you’re not even sure where to look.

Manta1

The show is really all about the manta rays, but just like Vegas, every once in a while we get a cameo so amazing it blows even the local divers minds.  No, I’m not referring to Celine Dion or Frank Sinatra, for us islanders we get giddy when a native Hawaiian Monk Seal appears on the show!

H01 Monachus schauinslandii watermarked

Don’t get me wrong, the manta rays are incredible, but I am more a mammal girl myself.  It’s what I focused on while obtaining my marine science degree right here on island and they have been the center of my careers since then.  Heck, they still occupy my life on my weekends when I volunteer.  But for those of you from New England and California I’m sure you are saying “seal, What’s exciting about that?”  Well, let me tell you.

Currently, there are only about 1,000 of these seals left in the world and they are only found in the Hawaiian archipelago.  Of those thousand animals only about 6 of them are residents to our Big Island.  And of those 6, one of them has found an affinity for our Manta Ray night dive.  This individual, one of a few very highly endangered seals, is named Waimanu.  Born in Waimanu valley (they got really creative with names, huh?)  she is a gorgeous, chubby 8 year-old pinniped.  Some may live to be between 25-30 years old, so Waimanu is a relatively young girl.

Monk seal yawn copy

That being said, she has already been a mom twice, that we know of… Unfortunately, even with all the watchful, helpful eyes of the locals, neither pup (baby) made it.  This is the reality with these animals. They are endangered by unrelenting pollution, trash, wayward and discarded fishing line, hooks, and even reduced prey source.

I am proud to say that our community is working to protect all our ocean wildlife.  In the past few years we have banned plastic shopping bags completely. There is currently a bill to ban one use plastics (Styrofoam, plastic utensils, etc.) so less of it ends up in our oceans. We are also constantly participating in beach clean-ups and ocean clean-ups.  We make sure the fish we chose to eat is locally and sustainably caught.  There is even a hospital in Kona specifically set-up to rehabilitate Hawaiian Monk Seals (Ke Kai Ola).  I’m more than proud to call this place home and even more proud to call Kona and Kona Honu Divers my community.

So why is it exciting to see Waimanu?  Maybe it’s partly because she’s a highly endangered species, maybe it’s because she’s an extremely graceful, big, beautiful animal, maybe it’s because she has an extremely cute face that melts your heart.  For me, it’s exciting to see her because she is a part of our community, a contributing member just like the rest of us and every time we see her it inspires us to be stewards to our ocean and share the love with our guests.  Plus, let’s face it, it is just cool!

-Tara Spiegel

 

 

Black Water: Squid

Most squid, Sthenoteuthis included, have less than a year to be born, grow, and reproduce before they expire.  This translates into an incredibly high metabolism. Young squid in captivity can eat nearly half their body weight five times per day 2.5 times their body weight per day! That would be like me eating 450lbs of food!  Adult Sthenoteuthis are easily the most common cephalopods we see on blackwater dives.  They can be seen as the large shoals the edges of our lights as we drift through the pelagios on our bi-weekly Black Water Dive.

Sthenoteuthis oualaniensis school small watermarked (1)

This week we get to meet the anomaly that is the purpleback flying squid (Sthenoteuthis oualaniensis).  They are called “flying squid” because, like Exocoetids (aka flying fish) they can leap and glide across the surface of the water to escape predators that skirt the edges of our lights as we drift through the pelagios.  They spend their days hiding in a region between 200-1000 meters deep in the midwater known as the oxygen minimum zone.  This is an area where animals with higher metabolic demands cannot sustain their bodily functions due to low levels of available oxygen.  So while the low oxygen levels keep the squid safe from their most fearsome predators like tuna, the squid itself requires large concentrations of oxygen as well, thus the conundrum.  It turns out that squid kept in tanks containing low-oxygen water can shut their metabolism down to a tenth of the normal rate of consumption.  This means that the squid may not only be hiding from predators in the oxygen minimum zone, but it may be using the cold, dark, low-oxygen environment of the OMZ to shut down its metabolism and wait out daily periods of low-foraging opportunity when the squid would otherwise just starve.

Sthenoteuthis ouahaniensis small watermarked (3)

Sthenoteuthis oualaniensis watermarked (1)

Pan-tropical spotted dolphins (Stenella attenuata) often come in to forage on the schools of Sthenoteuthis attracted to our lights.  One night, a dolphin pod came in to dine and hit the squid school just under the water’s surface.  I watched this shiny object drifting down under the scene and recognized it as a squid’s eyeball drifting into the blackness.

Squid Eyeball 2 watermarked (1)

-Jeff Milisen

MSc.

http://milisenphotography.yolasite.com/

Nudibranchs

Nudibranch (pronounced noodabrank) means “naked gill”.  This refers to the gill-like appendages sticking out of the backs of most nudibranchs and is the organ that allows them to breath.  Most nudibranchs also have appendages called rhinophores, usually located at the head.  These have scent receptors and are used to taste, smell, and navigate.  Most nudibranchs can retract these tentacle-like organs into a pocket in their skin so they are protected from hungry predators.

Nudibranchs are Gastropods in the phylum Mollusca. They are related to snails, slugs, limpets, and sea hares.  Unlike other mollusks nudibranchs do not have shells as adults.  The shell is only found in the larvae stage and disappears when it becomes an adult.

There are over 3,000 species of nudibranchs and new species are being added to the list all the time.  Nudibranchs come in all sizes from just a few millimeters to over 12 inches and weighing up to 3 pounds like the beautiful Spanish dancer.   They can be a myriad of colors, spotted, striped or solid with trim. They are found in cold temperatures and warm temperatures.

There are two main types of nudibranchs dorids and eolids.  The dorids breathe through gills that are located on their backs in a cluster.  Eolids have appendages called cerata that can cover their entire backs and can be threadlike, club-like, branched or clustered in several groups.  The cerata have multiple functions including breathing, digestion, and defense.

Nudibranchs see only light and dark.  Information about their environment is gathered by the rhinophores or sense of smell and some by sense of taste through tentacles surrounding the mouth.  Nudibranchs and all other mollusks, have a radula, an organ with many tiny teeth, which they use to scrape up food.  All nudibranchs are carnivorous.  They feast on a variety of foods including sponges, hydroids, anemones, fish eggs, barnacles and even other nudibranchs.  Some species dine exclusively on one type of food and one species of that food.

The colors of nudibranchs come from the colors of the foods they ingest.  Color can camouflage them or, when bright and flamboyant, signal to predators that they are poisonous.  Some nudibranchs eat corals that contain algae. They absorb the algae’s chloroplasts and store them in their cerata where the chloroplasts will continue to photosynthesize and supply the nudibranch with nutrients.

What they eat can also supply a means of defense.  Eolid nudibranchs that eat organisms that have nematocysts, or stinging cells, can store them in their cerata and use them to sting predators if they are attacked.  Some dorid nudibranchs, like the fried egg nudibranch, have a unique defense system.  They secrete toxic slime that stinks and mucks up the water, warding off would-be predators.  True to their classification as slugs they do very little work to prepare these defenses. They simply absorb toxins manufactured by the foods they eat.  Not to stereotype the character of all nudibranchs, there are some industrious species of nudibranchs that manufacture their own toxins.

The majority of nudibranchs cannot harm humans.  Two exceptions are Glaucus atlanticus and a close relative Glaucus marginata.  They eat Portuguese man-o-war, absorb the nematocysts, and can use them to cause a pretty nasty sting even to humans.

All nudibranchs are hermaphrodites which means one individual is both male and female.  The lucky little guys can mate with any individual that happens by.  This is a plus because during the majority of a nudibranchs life they live alone and searching for a mate is inhibited by the fact that they never move very far and they can’t move very fast.  When two adults meet they each extend a tubular organ that they connect together and through this they fertilize each other’s eggs. The eggs are deposited in a spiral pattern, all rings evenly spaced from one another.  They are suspended in a gelatinous substance that holds them in place and gives the egg mass a ribbon-like appearance.  The larger “ribbons” of the Spanish dancer eggs can even look like an underwater rose.

Sadly nudibranchs don’t live very long.  Some live up to a year but most live only a matter of weeks.

Facts about some common Hawaiian nudibranchs:

Phyllidiidae varcosa, more commonly known as the Scrambled Egg Nudibranch or the Fried Egg Nudibranch.  The latter name seems more fitting to me because the white ridges on the body with the yellow spots resemble an egg white and yolk.  These are very commonly seen in the waters off Kona.  An individual can reach up to 3.5 inches (14cm) in length. They are common throughout the Philippines and the Indo-Pacific too.  The fried egg nudibranch, like all other Phyllidiidae species, will secrete a toxic mucous when disturbed.  This excretion is deadly to other marine animals.  The toxin comes from sponges they eat.  They eat the toxic sponges than store the toxin in their bodies to use as a defense mechanism.

Fried Egg Nudi (1)

Glossodoris rufomarginata also known as the White Margin Nudibranch is another species seen in Kona.  It is also found in other areas of the Indo-Pacific and the Red Sea. These are small nudibranchs ranging from 1-2 inches (2.5 to 5cm).  They will be found in depths of 15 to 100ft (5 to 30m) but I usually see them in the 25 to 35 foot (8-12m) range hanging on the ceilings of arch formations.

White Margin Nudi

Halgerda terramtuentis, the gold lace nudibranch, is endemic to Hawaii which means it is only found in Hawaiian waters.  They are abundant in Hawaii and can be found in shallow waters usually no deeper than 30ft (10m).  They grow to a maximum of about 2in (5cm).

Gold Lace Nudi

Pteraeolididae ianthina, or blue dragon nudibranch is an example of a nudibranch that gets its color from the food that it eats.  They eat hydroids that have zooxanthellae living in them.  The zooxanthellae photosynthesize to produce nutrients and this also produces the color that is transferred to the nudibranch when it eats the hydroid.  Curiously, just like plants, the zooxanthellae can produce different colors so the “blue” dragon nudibranch can be colors other than blue.  In Hawaii I have only seen blue colored blue dragon nudibranchs but they are found throughout the Indo-Pacific in various colors.  No matter the color of the body, they all have purple band markings on their oral tentacles. These nudibranchs also ingest the nematocysts of the hydroids, store them in their cerata and use them for self-defense.

Blue Dragon Nudi

Hiatodoris fellowsi is another endemic nudibranch.  Its common name, Fellow’s Nudibranch.  They are named after biologist David Fellows who was the first to collect a specimen.  These are strikingly beautiful nudibranchs with their snowy white bodies and contrasting jet black gills and rhinophores.

White Margin Nudi

~Stacey Herman

Black Water: Beroe

Meet the Beroe

This week we celebrate the genus of ctenophores known as Beroe.  Ctenophores as a group all move by coordinating rows of beating cilia.  They occupy all marine ecosystems, can be quite large and their beauty will entrance even seasoned blackwater divers.  They have limited few rudimentary senses and no central nervous system.  Instead, they have a nerve net around the mouth. Ctenophores are hermaphrodites, thus they do not have male and female sexes and selfing-or self fertilization- has been observed in some species.  Unlike typical jellies in the phylum cnidaria, ctenophores do not produce nematocysts but can recycle nematocysts from cnidarian prey.  Instead, some species have cells called colloblasts that shoot an adhesive substance at prey. Most of the ctenophores that we observe on blackwater dives are clear and lack bioluminescence.  The brilliant colors that we see are simply our own lights refracting off the body of the animal.

While most other ctenophores play an important role in preventing over-abundances of copepods and small fishes in pelagic environments, the 24 species of Beroe keep their close cousins in check by eating other ctenophores.  They have evolved a sac-like body form that is capable of expanding to envelop and pinch off other gelatinous animals.  Beroid 5 watermarkedCtenophore Beroid watermarked
-Jeffrey Milisen
MSc.

Black Water: Salp

A single salp oozoid that will never get laid.
Salps are the most common organism in the epipelagic environment and thus, far and away the most common animals we see on a blackwater.  Unlike most of the blackwater inhabitants, salps, aka tunicates or sea squirts, share our Phylum chordata.  That means that at some point in their lives they have a notochord.
I will be the first to admit that all of this taxonomy isn’t very interesting, so lets change the subject to sea squirt sex.  The individual oozoid stage is asexual and reproduces by selfing or making a whole bunch of genetic copies of itself in the form of a chain that can either be circular (cyclosalpa) or in a long string (salpa).  These chains are composed of a bunch of individuals known as blastozooids which are all attached by a complex network of “plaques” or information sharing connections that allow the salps to swim in a coordinated, synchronized fashion.  The blastozooid, or colonial, phase of a salp is the sexual one.  To simplify this, if you lived life like a salp, your kids, the result of sex with your spouse (or the mailman-we don’t judge at KHD!), would spawn a bunch of identical twins (reproduction through parthenogenesis) that would then go off to find someone else to reproduce with.
Are you creeped out yet?  No?  Because it gets weirder.  The blastozooid, or sexual form of a salp, undergoes sequential hermaphroditism. So they are females that produce female gametes (eggs) when they first mature, but eventually change sex into males as they get older.  While this process seems very complicated, it is also very efficient.  Salps can reproduce almost as fast as some bacteria!  That means that when conditions are just right (lots of phytoplankton food) they can bloom and inflict severe repercussions on the local plankton productivity.

Cyclosalpa blastozooid 2 small watermarked

Argonauta watermarked

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Cyclosalpa blastozooid colonies-These are many salp zooids in their sexual phase.

Phronima and eggs small watermarked

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The empty cavities of salp zooids are habitat for a whole host of organisms.  Look for crustaceans like this phronima, argonauta octopodes and even fish inhabiting the interior of salps.Salp oozoid 2 watermarked

Amphipods on pyrosome watermarked (1)

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Pyrosomes: A different kind of salp

-Jeffrey Milisen
MSc.