For my end of semester project I chose to study nudibranches, after researching and finding out there are 3000+ known nudibranch species1
"There are more than 3,000 known nudibranch species, and scientists estimate there are another 3,000 yet to be discovered."
- National Geographic Nudibranch Gallery, I narrowed it down to Okenia rosacea, the Hopkins' Rose Nudibranch, because I had never seen them in northern california before this year [2016], woo thanks to Genna spotting them at Pillar Point!
MIDWATER DIVE : Plankton
Nereid Polychaete
Kingdom Animalia
Phylum Annelida
Class Polychaeta
Order Phyllodocida
Family Nereidae
Genus Platyneresis
Species P. dumerilii
More Info ⤴︎X
The National Oceanic and Atmospheric Administration (NOAA) ship Okeanos Explorer and Nautilus Live have ocean expeditions live streamed throughout the year (they're amazing and I totally recommend checking them out), this project was inspired from watching all the life in the midwater column passing through the view on the way down to the main location and back up to the ship. If you had a microscope.. in your eyes.
Click on each little plankton photo to learn more about them, and follow the "more info" link for REALLY COOL videos and articles specific to each organism. Yay plankton!
Images: D. brightwellii[1][2], T. lineatus[1], N. scintillans[1][2], A. punctulata[1][2], P. dumerilii[1][2], P. pileus[1][2], P. marinus[1][2], P. physalis[1][2]
Plankton are organisms that drift with the currents and are unable to swim against them, they vary in size and .. well pretty much everything and because of this it can be a bit difficult to wrap your head around how a jellyfish the size of an umbrella and a little microscopic crustacean larva, or.. like literally algae, can all be called plankton.
The activities of the microscopic vegetables of the sea, of which the diatoms are most important, make the mineral wealth of the water available to the animals. Feeding directly on the diatoms and other groups of minute unicellular algae are the marine protozoa, many crustaceans, the young of crabs, barnacles, sea worms and fishes. Hordes of the small carnivores, the first link in the chain of flesh eaters, move among these peaceful grazers. There are fierce little dragons half an inch long, the sharp-jawed arrowworms. There are gooseberry-like comb jellies, armed with grasping tentacles, and there are the shrimp-like euphausiids that strain food from the water with their bristly appendages. Since they drift where the currents carry them, with no power or will to oppose that of the sea, this strange community of creatures and the marine plants that sustain them are called ‘plankton,’ a word derived from the Greek, meaning 'wandering.' *
* From The Sea Around Us, by Rachel L. Carson, p. 21
One thing that's helped me understand is the movement with the currents, jellyfish are able to move vertically in the water column but still have no control in where they end up and must go where-ever the water takes them. Other plankton like the larvae of most crustaceans are so small that they’re little legs or appendages don’t really do much outside their miniature world, they move fast under a microscope but the area they occupy is so tiny that they’re movement is flowing with the currents they're confined in.
Since there are so many drifting organisms there are different ways to classify them based on their trophic group (how they get nutrients), lifestyle, or size.
- Trophic Group
- Zooplankton
- Animal-like plankton, consumers that obtain their energy by feeding on phytoplankton and other zooplankton
- Play an important role in the marine food web as the primary herbivores feeding on phytoplankton, providing an important link between the primary producers and larger consumers.
- Phytoplankton
- Microscopic marine organisms that produce their own food using energy from the sun and carbon dioxide - photosynthesis!
- Primary producers in the marine food web providing the food base for most almost all life in the marine environment.
- Bacterioplankton
- Single celled producers and/or consumers (some are autotrophicAutotroph
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Organisms that can produce their own food, using materials from inorganic sources. The word "autotroph" comes from the root words "auto" for "self" and "troph" for "food." An autotroph is an organism that feeds itself, without the assistance of any other organisms.
- Biology Dictionary and some are heterotrophicHeterotroph
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A heterotroph is an organism that eats other plants or animals for energy and nutrients. The term stems from the Greek words hetero for "other" and trophe for "nourishment".
- National Geographic Encyclopedia) consisting of bacteria and archaea - Very important role in the marine food web breaking down organic material and making nutrients available for phytoplankton and other organisms
- Single celled producers and/or consumers (some are autotrophicAutotroph
- Zooplankton
- Lifestyle
- Holoplankton
- Planktonic their entire lives, consists of phytoplankton and zooplankton
- Meroplankton
- Planktonic for only part of their live cycle, usually during the larval stage. Also consists of phytoplankton and zooplankton.
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Two of my favorite examples of meroplankton and the ways that some organisms change through their life are with jellyfish and sea urchins, the diagram to the right/above shows the life cycle of Aurelia aurita, a moon jelly. They start and end their life as plankton and are benthic Benthic
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The term benthic refers to anything associated with or occurring on the bottom of a body of water. The animals and plants that live on or in the bottom are known as the benthos.
- National Oceanic and Atmospheric Administration (NOAA) organisms inbetween, living as crazy polyps that basically throw off little jellyfish that then live back in the water column. The process is a form of asexual reproduction called strobilation, where a new organism grows out from the body of the parent organism in repeated segments, and is the most common way for an ephyra to form. Sea urchins start out like little plankton space ships and end up on the floor as benthic organisms, this short video from KQED Deep Look by Joshua Cassidy and Carrie Boyle, Sea Urchins Pull Themselves Inside Out to be Reborn, goes into detail about their (sometimes ridiculously long) life cycles.
- Holoplankton
- Size
- Femtoplankton 0.02 - 0.2 μm
- Picoplankton 0.2 - 2 μm
- Nanoplankton 2 - 20 μm
- Microplankton 20 - 200 μm
- Mesoplankton 0.2 - 20 mm
- Macroplankton 2 - 20 cm
- Megaplankton 20 - 200 cm
- Notes
- Algae Base and the World Register of Marine Species are super helpful resources to see the distrubution and taxonomy of marine organisms.
Noctiluca scintillans Bioluminescence TOP
My first experience with bioluminescent plankton was on a field trip - the “8th grade field trip”. I remember being incredibly seasick on a ship slowly heading towards Catalina Island, and how the only criteria for going on the night swim was that we had to watch a documentary about all of the amazingly terrifying deep sea creatures that live in the ocean before we got into the water with them.
Even though we could see below on a video feed, and knowing that we weren’t in a deep area, it still wasn’t the most calming thing to watch right before jumping into the ocean off of a giant ship at night. But when I opened my eyes underwater I could see the silhouette of everyone around me, and it was weirdly comforting to be surrounded by tiny bioluminescent animals.
scintillans (latin)
sparkling
A hard, brilliant, coruscating phosphorescence often illuminates the summer sea. In waters where the protozoan Noctiluca is abundant it is the chief source of this summer luminescence, causing fishes, squids, or dolphins to fill the water with racing flames and to clothe themselves in a ghostly radiance. - From The Sea Around Us, by Rachel L. Carson, p. 39.
Annd now science! Noctiluca scintillans light up when their agitated, possibly to ward off predators when they feel under attack, another idea is that they act a bit like an alarm to draw in other predators that threaten the original predator.
They are able to luminance because of a luciferin-luciferase chemical reaction within the cell and are one of the most common bioluminescent plankton in neritic Neritic zone
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The area of the ocean that extends from the low tide line to the edge of the continental shelf, a depth of roughly 200 m [656 ft].
- Indian Ocean Tuna Commission and coastal regions, the video below by Peter Kragh demonstrates this effect with waves in an area with a high concentration of bioluminescent dinoflagellates, the red tide in San Diego 2011 (a bloom!).
Dinoflagellate luciferin is very similar in structure to some types of chlorophyll, and is thought to be derived from it. The Latz Laboratory at Scripps Institution of Oceanography studies bioluminescence and its role in marine ecosystems, the excerpt below from Dinoflagellate Bioluminescence explains some of what is known about the process.
The cellular regulation of dinoflagellate bioluminescence is complex and only partially understood, but the luminescent chemistry is ultimately caused by a drop in pH due to an influx of protons within the cell. The time from stimulus to light emission is less than 20 ms, making it one of the most rapid cellular processes known. Each dinoflagellate cell can produce more than one flash, which lasts on the order of 100 ms. However, the bioluminescence capacity of a cell is depleted once all its available luciferin has been oxidized. But during the next day it can recharge the chemicals to flash again the following night.
Noctiluca scintillans Algal Blooms TOP
During the day the name red tide makes much more sense, N. scintillans are dinoflagellates without chloroplasts Chloroplasts
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The chloroplast, found only in algal and plant cells, is a cell organelle that produces energy through photosynthesis. The word chloroplast comes from the Greek words khloros, meaning “green”, and plastes, meaning “formed”. It has a high concentration of chlorophyll, the molecule that captures light energy, and this gives many plants and algae a green color.
- Biology Dictionary and are unable to photosynthesize on their own, it’s because of the organisms they prey on, diatoms, ciliates, and other phytoplankton that do have chloroplasts and are able to photosynthesis, that they get their color and are able to bioluminesce through a process called endosymbyosis.
[ Image from the Sydney Morning Herald ]
This also explains why they can vary in color so drastically, because their bodies are transparent their color depends on the organisms that they consume. N. scintillans consume algal cells by phagocytosis Phagocytosis
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The process of digestion of solid substances by cells. In this process, the cell surrounds the particle and engulfs it.
- Topper Learning after, some cells are digested and others stay as symbiontsSymbiont
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Term used to refer to an organism living in a symbiosis. Symbiosis is a close and prolonged interaction between organisms of different species.
- Biology Online. In most microalgal symbioses, symbionts are enclosed in membranes inside of the host cell and material exchange occurs through the boundary of the membrane, the quote below from Endosymbiosis in microalgae with special attention to Noctiluca scintillans [2006] explains one way the green N. scintillans differs and talks a bit more about color variation.
One exception is found in the symbiosis of a heterotrophic dinoflagellate Noctiluca scintillans with a photosynthetic green flagellate Pedinomonas noctilucae. A large number of symbionts swim freely within the host cell without being enveloped by any membranes. While N. scintillans in temperate waters forms distinct reddish red tides, those in tropical Southeast Asia and adjacent areas have greenish discoloration due to the presence of the symbiont. For this reason, it is often called the "green Noctiluca"
[ Image from NASA Earth Data ]
Something that’s interesting to think about is how plastids (chloroplast!) and the mitochondria in eukaryotic cells both have double membranes, and probably formed through similar processes. Mitochondria starting out as free swimming bacteria-like microorganisms being engulfed by the cell and then coming to live inside as a symbiont early on in their evolution. And now, the algae that N. scintillans consumes being able to photosynthesize because of the same process happening so long ago. Both resulting in double membranes: one from the original and a second from the cell as it wrapped around it.
Less than 1% of blooms actually produce toxins, and N. scintillans fall into the larger category of non-toxic species, though they can still be a cause for benthic animal and fish mortality because of eutrophication. Since blooms are normally followed by the organism that was in such a high concentration dying off - and decomposition is accompanied by oxygen consumption - this can strip the water in the surrounding area of available oxygen and lead to either hypoxia (low oxygen) or anoxia (no oxygen). Most marine life cannot survive without oxygen so hypoxia or anoxia will usually result in another mass die off consisting of fish, shellfish and other marine life. The main reason of crustacean death is caused by algal cells becoming trapped in their gills resulting in respiratory failure, bacterial infection, or hemorrhaging. This video from Fuse School talks about the process in more detail.
Algal blooms occur when the organisms have an excess of nutrients and can thrive and grow out of control, one example with N. scintillans from January of 2015 was when the coasts of Hong Kong were lighting up with blue bioluminescence (much like the video above from the red tide in San Diego). The bloom was brought on by agricultural run off, fertilizers and chemicals that spread from inland to the sea by rain - so in essence they were a bit like a very pretty, flashing “things are different” alarm and highlight how even small single celled organisms can have such a huge effect on the surrounding environment and life.
End of Semester Project: Okenia rosacea TOP
Week one: Introduction
Week Two: Water Planet
Okenia rosacea is a heterotroph"A heterotroph is an organism that eats other plants or animals for energy and nutrients. The term stems from the Greek words hetero for "other" and trophe for "nourishment"."
- National Geographic Encyclopedia, it feeds on the pink encrusting bryozoan (Integripelta bilabiata) and has teeth that have adapted into hooks,
that can reach inside the bryozoan and pull out the zooids2"It eats just one filter-feeding animal called the “pink encrusting bryozoan” (once known as Eurystomella bilabiata, now Integripelta bilabiata). Bryozoans, commonly called moss animals, are superficially similar to coral. They both eat tiny organic particles floating in the water, they both form colonies of interconnected individuals, and they both have hard, boxy cells that house a single organism (for coral this organism is called a polyp and for bryozoans it’s called a zooid)"
- Kaitlyn Kraybill-Voth, Bay Nature Institute
, feeding on only the pink bryozoan is also how it gets its color because of a carotenoid"Carotenoids are a class of more than 750 naturally occurring pigments synthesized by plants, algae, and photosynthetic bacteria. These richly colored molecules are the sources of the yellow, orange, and red colors of many plants."
- Micronutrient Information Center, OSU pigment called hopkinsiaxanthin3"The striking, rose-pink color of Hopkinsia rosacea is due to the presence of a carotenoid pigment, hopkinsiaxanthin."
- Harold H. Strain, Hopkinsiaxanthin, a Xanthophyll of the Sea Slug Hopkinsia Rosacea, page 209
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[ Hooked tooth of Okenia rosacea by T.M Gosliner from Sea Slug Forum. Scale bar = 400 µm ]
[ "Pink Elements on Parade - Hopkins' Rose Herd at Pillar Point" by yawnthensnore ]
Since nudibranches have no shells and don't fossilize well to get an idea of how long they've been around you need to piece together known ages of fossils from their shelled relatives (class: Gastropoda), and the larger group that they belong to (Phylum: Mollusca), using this approach scientists have been able to estimate that nudibranchs date back to at least 180 MA4
"By dating fossils of some of their shelled relatives and looking at the ages of some of evolutionary lineages to the larger group to which they belong, we have been able to establish a molecular clock of how old these groups might be. We have been able to estimate that the nudibranchs are quite old as a group, probably dating back to at least 180 million years ago."
- Terry Gosliner, California Academy of Sciences, Nudibranchs, Philippines, Photography, Q & A.
Found from Coors Bay, Oregon to Isla San Martin, Baja California in shallow tidal zones5
"This species was originally described from Monterey Bay, California (MacFarland 1905) has been found from Coos Bay, Oregon to Isla San Martin, Baja California (Behrens 1991)."
- April 22, 2004 Proceedings of the California Academy of Sciences Volume 55
. Nudibranches are plankton in their larval stage so they drift with currents until they settle and grow into adults. Since where they end up is affected by currents and upwelling they are mainly found in warmer southern california waters, when winds slow and currents shift (like when el nino happens) they can be found in greater numbers farther north6
"The eggs then hatch into microscopic larvae that float passively until they are swept into a warm shallow tidal zone."
- Kaitlyn Kraybill-Voth, Bay Nature Institute
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Week Three: Plate Tectonics
Because the Rose Nudibranch needs shallower warmer water to survive they are affected by features produced through plate tectonics, some of them are continental shelfs and islands/island chains7
"As a consequence of plate tectonics, oceanic shallow water habitats worldwide are characterized by a great dissimilarity of area and geography."
- Hans BertschBook, Review of Indo-Pacific Nudibranchs and Sea Slugs (Gosliner, Behrens & Valdés, 2008)
formed by converging plate boundaries or plates moving over hotspots, since they provide areas where the ocean is shallower and more sunlight is able to reach through.
Week Four: Seafloor/Sediments
At Pillar Point they were mainly attached to Sea Grass and Algaes in shallow tidal pools, since their food is encrusting and found over rocks some were also sticking to the rocks just above the tide, without water around them they flatten (their gills, dorsal papillae and rhinophores8
[ Image by Gary McDonald ]
Gills
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The respiratory organ of most aquatic animals that obtain oxygen from water, consisting of a filamentous structure of vascular membranes across which dissolved gases are exchanged.
"Their scientific name, Nudibranchia, means naked gills, and describes the feathery gills and horns that most wear on their backs."
- National Geographic
Dorsal Papillae
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Cerata-like structures, the branched little spikes coming off of the top/sides of Okenia rosacea, more information can be found in this post from the Sea Slug Forum.
Rhinophore
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Scent or taste receptors, also known as chemosensory organs situated on the dorsal surface of the head. The "scents" detected by rhinophores are chemicals dissolved in the sea water.
stay down) and they look like a sticky, pinker verson of their food. And also a lot like chewed up bubblegum. They live in depths up to 6 meters in the rocky low intertidal zone9
"Low intertidal to 6 m"
- David Cowles, Invertebrates of the Salish Sea
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[ Okenia rosacea, Pillar Point November 25, 2015 images by mee ]
Week Five: Seawater
The water clarity at Pillar Point was a bit cloudy and hard to see through in some areas, but most of the pools that I could see nudibranches in were shallower and clear enough to see to the bottom where there wasn't algae or sea grass.
The sea surface temperature (SST) of Half Moon Bay, closest area to Pillar Point I could find data from, during November was highest at the begining of the month at 16°C (61°F) and stayed mainly between 13-14°C (55-57°F) throughout the rest of the month. Looking at the past few months November seems to be colder, the SST was mainly staying above 15°C (59°F) from July through October of this year (2015), looking at the average SST of Monterey, CA where they are normally common for this time of the year they match up pretty well at 13°C (55-56°F) for the Rose Nudibranch temperature needs.
| Location | June 2011 | June 2012 | June 2013 | June 2014 | June 2015 |
|---|---|---|---|---|---|
| Half Moon Bay | 12°C/54°F | 12°C/54°F | 13°C/55°F | 13°C/55°F | 13°C/55°F |
| Monterey | 13°C/55°F | 12°C/54°F | 13°C/55°F | 14°C/57°F | 14°C/57°F |
| Data from www.seatemperature.info USA water temperatures | |||||
Nudibranchs have been found in all depths of the ocean from the intertidal zone (Okenia rosacea!) to over 2500m10
"..discovered at a depth near 2,500 meters in Monterey Bay. It has been tentatively classified as a nudibranch but it is unlike any other member of that group ever described."
- Monterey Bay Aquarium Research Institute, Discoveries of deep-sea biomass and biodiversity using an ROV
, since Okenia rosacea is found in shallow waters I don't think that it would survive pressures greater then it's use to, also, it would most likely die because of the temperature drop with depth and it's food only being available in depths from -0.5-22m11
"Depth range (m): -0.5 - 22"
- Integripelta bilabiata details and map Encyclopedia of Life
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[ Image from Regional Ocean Modeling System (ROMS) by the UC Santa Cruz Ocean Modeling Group ]
Sea-surface salinity of Pillar Point stays around 33 parts per thousand (ppt), salinity varies greater in shallow areas like tide pools because small changes can have a greater effect, since nudibranchs are sensitive to changes in their environment salinity needs to stay steady for them to thrive. The same goes for acidity, this year average pH of Monterey is 8.0 and 7.8 in Humboldt so they must be alright within those ranges since they've been found in areas along the coast from Monterey to Humboldt (and even farther north up to Oregon).
Week Six: Atmosphere
The main atmospheric condition that Rose Nudibranchs are affected by is solar energy, if the water isn't warm enough they wont survive, and the organism that they eat wont survive to begin with. Since their food source is found throughout the Pacific Coast (as far north as British Columbia) if the water temperature is warm enough they can survive farther north if the current brings them there - or boats, ah!
Seasonal Variations: There were quite a few adult and juvenile nudibranchs in November at Pillar Point, since they only live around a year, take a few months to develop, and breed inbetween spring and summer (northern hemisphere) I would think there would be seasonal variations, possibly more during fall and winter (aug/oct/nov) then there are during the end of summer after they've laid eggs.
Week Seven: Currents
[ Image from Teach Ocean Science showing how currents can effect whether organisms live or die, example with crab larvae showing how some are carried out to areas with low nutrients and others to areas that fit their needs. ]
Nudibranchs are planktonic in their larval stage and are moved around by currents, because of that they rely heavly on the currents to survive since they can be swept into areas that don't fit their needs (too cold, no pink bryozoans, etc). If the conditions do fit their needs they have no problem surviving, this is what is happening now along the coast of california and why this kind of nudibranch is being found farther north, since winds have been from the south more then usual their larvae may be being carried northward and towards the shore into tidepools where they can survive instead of away from the shore12
"Goddard explained; they are carried northward and onshore by coastal currents as microscopic planktonic larvae. When the larvae have fed and grown large enough — typically over a period of a month or two — they settle to the bottom. They metamorphose into juvenile slugs when they encounter the prey of the adults."
- Jeff Goddard via Julie Cohen, Roses Bloom in California Tide Pools
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Week Eight: Waves
[ Image from Oregon Tide Pools ]
Waves in the intertidal zones can be pretty intense since the water is shallower, the ocean floor pushes the waves up and there are things for waves to crash into like rocks, unlike in the open ocean where waves can spread out, up close to the shore there's no where else for the energy to go. Organisms that live mainly in the low tidal zone need to be pretty well adapted to handle the forces of waves since their zone is sometimes only exposed during extremly low or spring tides13
"Between the high and low tide marks likes a strip of shoreline that is regularly covered and uncovered by the advance and retreat of the tides. This meeting ground between land and sea is called the intertidal."
- California Coastal Resource Guide, California’s Rocky Intertidal Zones
, nudibranches have adapted to the harsher environment by moving with the waves instead of going against them, because of that their main issue with waves is not being thrown around and harmed but from drying out.
Week Nine & Ten: Tides and Coasts
Since the Hopkins' Rose Nudibranch can die from drying out tides are important for their survival, they stay in the low intertidal zone along coasts between the spring low tide and neap low tide where they can be somewhat protected in the tidepools from large preditors and close to their food source.
Along the coast in pillar point I saw the most nudibranches in tidepools holding on to sea grass or stuck to the side of rocks near by their food, some in deeper pools (still only a foot or two ) where there was a lot of green and brown algae around them and others were in shallower pools without much algae around on rocks on the sides of the tide pool.
Week Eleven: Marine Organisms
Classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Heterobranchia
Infraclass: Opisthobranchia
Order: Nudibranchia
Suborder: Euctenidiacea
Infraorder: Doridacea
Superfamily: Onchidoridoidea
Family: Goniodorididae
Genus: Okenia
Species: Okenia rosacea
Okenia rosacea is in the Mollusca phylum and are closly related to sea snails (which are included up until Order: Nudibranchia) both sea snails and nudibranchs have atleast one pair of tentacles that can't be withdrawn, and most also have rhinophores that they use like our noses14
"The word rhinophore is made from two classical Greek words rhino = nose, and phore = carrier, and is a reference to the function of the rhinophores as an organ of "smell". We smell scents and odours with our nose, which has special receptors to sense the chemical molecules in the air. In nudibranchs, and other marine animals, the same sort of chemicals are dissolved in the sea water."
- Sea Slug Forum
- the name rhinophore actually means "nose-carrier"!
Nudibranchs have been found at all depths of the ocean but Okenia rosacea stays along the coasts in shallower, warmer waters mainly on the sea floor as a benthic organism after its planktonic larval stages, like most nudibranchs, but there are some that do stay in the water colum their entire lives.
The viscosity of water can't be so high that they can't move freely through the water - since they "flow with" the water around them - if they have too much resistance they won't be able to get far. At the same time the viscosity can't be so low that they have no resistance to their apendages (tenticles!) which they use while moving.
For predators it doesn't seem like they have that many, though sometimes nudibranchs will eat other nudibranchs. Predators are warned off by their bright colors and bad taste, usually if they've tried one they're not going want another.
SPECIAL TRAITS OF OKENIA ROSACEA
· Hooked teeth to feed on specific diet
· Many appendages (Dorsal Papillae) to take up a greater surface area
· Bright colors
Nudibranchs are pretty amazing at using something that comes from something else, with Okenia rosacea it is it's bright pink color from eating only red bryozoans. Some nudibranchs even gain the ablitly to sting from eating hydroids, others are able to photosynthesize from the zooxanthellae they get from eating coral.
[ Image by Kevin Lee, May 27th 2005 shows multiple O. rosacea nudibranches with their food source and egg sac ]
Okenia rosacea are hermaphrodites (both male and female) which means they can reproduce by themselves or mate with other nudibranchs if there are any around15"Like other nudibranchs, Okenia rosacea is a simultaneous hermaphrodite. Equipped with both male and female reproductive organs, this species can mate with any other mature individual of the same species."
- Michael Ready, Cabrillo Field Notes, and the conditions are good. They lay their eggs in a clockwise spiral from the outside-in, moving counterclockwise16"The egg mass of this species is deposited beginning at the outermost point on the outside whorl, and proceeding in a counterclockwise direction (viewed dorsally) toward the origin or pole."
- Sea Slug Forum and if they are disturbed they will normally pick up from the point they were interupted. Their eggs are layed inside a mucous that supports and protects them from the environment. After hatching they will be planktonic larvae until they've grown large enough to settle on the bottom - usually around one or two months - and metamorphose into juveniles when they encounter their adult food source17"They metamorphose into juvenile slugs when they encounter the prey of the adults. For Hopkins’ Rose, this prey comes in the form of a rose-colored encrusting bryozoan — a type of colonial invertebrate commonly known as a moss animal."
- Julie Cohen, UC Santa Barbara News.
Week Twelve: Pollution/Human Interaction
Along the coast trash and pollution can build up from far away even if there arn't many local sources contributing to the polution, when you combine that with what can come from close by (pesticides, plastic and other garbage, soaps, etc) the intertidal zone is pretty delicate, and areas can get too polluted for some organisms to survive. Since Okenia rosacea isn't able to swim for miles to another location if the tidepools were to get too polluted they will die off.
Human interaction can be a huge problem in the intertidal zone as well because people love to look at things and explore, and sometimes don't think about or care of the effect that they have. Being carefull not to crush something (almost every step you take near tidepools!!) can be difficult even when you are paying attention - so when areas become popular sometimes things can change quickly.
[ Image from ohiocitizen.org ]