Tag Archives: Plankton

Winter: It’s Here But What Is It?

It’s getting cold! The wind is starting to blow! Rain is falling! The grass is starting to grow! The waves are getting bigger! IT’S WINTER!!

WinterBut what exactly is winter?

There are two kinds of winter, astronomical winter— having to do with the position of the earth and the sun ranging from the winter solstice to the vernal equinox— and meteorological winter— based on the annual temperature cycle and the calendar.

In California this manifests in shorter days, cooler temperatures, increased rainfall and onshore winds. Many animals begin to migrate south to  winter in warmer climates or find food.

Just as seasons affect life on land, changes are brewing in the oceans as well. Relative changes in sunlight, day length, wind and ocean temperature all impact phytoplankton— small, plant-like organisms at the base of our ocean’s food web— eventually working its effects throughout the ecosystem.

In the summertime, the dominant California Current sweeps cold cool nutrient rich water from the Alaska current down along the west coast while winds generally blow north to south. Because of the Coriolis Effect these winds veer westward and surface water is pushed offshore. As this water moves westward deeper, nutrient rich water rises to replace the migrating water in a process known as upwelling. In areas where upwelling occurs, phytoplankton blooms are common, attracting fish and other ocean life to the area.

As winter approaches, the wind shifts direction and the California Current meanders westward to be replaced by the northerly flowing Davidson Current. Strong winds from the south pull surface water to build up along coastal margins, resulting in downwelling— essentially the opposite of upwelling where warm surface water sinks down. Even though surface water temperatures may drop rapidly with the arrival of winter, deeper waters (below 200 feet) can actually become warmer due to the mixing with warmer surface waters and the northerly Davidson Current. This warming of deep water could benefit bottom dwelling fish which breed during the winter months.

Many beaches also undergo drastic changes. In the winter larger and more frequent waves pick up sand from the beach and move it offshore, sometimes forming sandbars that buffer beaches from storm erosion. Beaches can become rocky or appear to  disappear! But don’t worry, when the summer returns gentler waves bring the sand back on to the beach just in time to lay out and soak up the sun. Just don’t forget to wear sunscreen!!

By Sachiko Lamen







Let’s Take a Closer Look at Microscopes!

The ocean is filled with critters we can’t see with the naked eye. Microscopes are an essential tool for learning how organisms develop, identifying diseases, how pollution travels through food webs, and what life exists below our range of vision. Microscopes have revolutionized how we study marine science and there are more to them than meets the eye.

Microscope 3

Compound light microscopes in the CIMI Plankton Labs let us see into a smaller, thriving world. 

Photo credit: Alyssa Bjorkquist

Microscopes (“micro” = small, “scope” = to look at) come in different styles depending on how small of an organism a scientist intends to observe. Our student marine scientists at CIMI use compound light microscopes. These microscopes allow us to see plankton at 250 times greater magnification than plain sight! Although plankton—drifting animals—can weigh in at a whopping 5000 pounds (Mola mola, Ocean sunfish), a vast world of marine creatures are so small that they can only be observed with a microscope.Microscopes 1

Parts of the Compound Light Microscope

Photo credit: Pinterest

Microscopes look complicated, but their anatomy is simple enough to navigate. Once the microscopes are plugged in and turned on, a light illuminates the subject through a diaphragm to create a bright field of viewing. An eyepiece is connected to a rotating set of objective lenses. The eyepiece has a set magnification, but various high- and low-power objective lenses can be clicked into place to view organisms at different magnifications. The lenses point to a stage containing a glass slide with organisms of interest. These three main sections—the lenses, light, and stage—are all connected by a sturdy arm. Four knobs assist scientists in making microscopic observations. The coarse knob moves the entire stage up and down, cutting through different layers in the sample to focus the main image in the eyepiece. The fine knob can make minute focusing adjustments to see different layers of an organism. Finally, translational knobs move the slide left, right, up, or down in the bright field so one can explore everything in the sample.

It only takes a few minutes to prepare a microscope for use! Simply turn on the microscope, put a drop or two of freshly filtered seawater from a plankton tow onto a glass slide, then insert the slide into the stage. With both eyes open, look through the eyepiece and focus carefully using the coarse adjustment knob. Once a subject is centered in your field of vision with the directional knobs, you can adjust the fine focus knob to explore the organism at the current magnification or switch to a more intense objective lens for closer magnification.


Left: Squinting with one eye is an efficient and harmful way to look into a microscope.

Right: Having both eyes open, but covering the unused eye, is a professional and safe method!

Photo credit: Alyssa Bjorkquist

Once you become more familiar with microscopes you can improve upon your observation skills. For example, professional biologists that look at microscopes for hours on end avoid eye strain and fatigue by using both of their eyes to view an image. Instead of squinting and using only one eye like introductory scientists, they train to keep both of their eyes open even when using a microscope with only one eyepiece. Practice using both of your eyes by covering the eye not looking through the eyepiece with one of your hands. With practice, you can observe countless organisms like a professional marine scientist!

To learn how to make your own microscope at home for $5, follow this link: http://www.pbs.org/wgbh/nova/tech/DIY-microscope.html

To learn about microscopes are being made accessible to millions, watch this inspiring TED talk: https://www.ted.com/talks/manu_prakash_a_50_cent_microscope_that_folds_like_origami

To explore microscopes in a fun, interactive activity check out this lab: https://www.brainpop.com/games/virtuallabsusingthemicroscope/

Follow this link for a virtual biology microscope lab: https://www.pbslearningmedia.org/resource/f4f6097a-807f-4488-b874-0bae0d8446c8/microscope-activity/en/#.WP-HHdLyvIU

If you have access to a microscope, check out this website for different things to look at: http://www.cas.miamioh.edu/mbi-ws/microscopes/activites.html


  1. Microscope anatomy: https://s-media-cache-ak0.pinimg.com/originals/ef/5e/bb/ef5ebba38c6216f7dc791395f482b579.jpg


  1. Introduction to Compound Microscopes: http://www.labessentials.com/microscopes_compound_basics.htm
  2. History of the Microscope: http://www.history-of-the-microscope.org/history-of-the-microscope-who-invented-the-microscope.php
  3. Compound Microscope Accessibility: http://www.microscopemaster.com/compound-light-microscope.html

Jellies: Squishy Mysteries of the Sea

Jellies are a rare and beautiful surprise on Catalina Island. They drift past surprised snorkelers in our coves, showing off vibrant colors and graceful tentacles as they float by. Although they are not a regular visitor, Catalina Island boasts a wide diversity of jellies ranging from microscopic hydroids to 12-foot Purple-Striped Jellies.


Purple-Striped Jellies have beautiful colors and possess long oral arms used for catching prey.

Photo credit: Monterey Bay Aquarium

Scientists use the phrase “jellies” instead of “jellyfish” to accurately represent the wide diversity of aquatic floating gelatinous organisms. Unsurprisingly, jellyfish are not actually fish—they lack a backbone and are 95% water. Organisms in the phylum Cnidaria first arrived in the fossil record 714 million years ago and are the first animals to evolve to a multi-organ system. The most famous “true jellies” belong to the class Scyphozoa, meaning that they have a bell-shaped body form for part of their life, possess tentacles or oral arms, and utilize stinging cells for capturing prey. Other gelatinous organisms often mistaken for true jellies include comb jellies (phylum Ctenophora). Although comb jellies look alike to true jellies, have a similar diet, and live in similar habitats they have colloblasts for obtaining food and have rows of cilia that propel them through the water.

CIMI staff and students can see tiny jellies while gazing into microscopes in the Plankton Lab. Small pulsating tentacle buds on a microscopic scale are enough to brighten any curious scientist’s day. Many 2mm species float by during a nighttime snorkel and are only detected with a bright torch. And still, other larger species such as Purple-Striped (Chrysaora colorata), Pacific Sea Nettle (Chrysaora fuscescens), Egg Yolk (Phacellophora camtschatica), and Moon jellies (Aurelia aurita) can be seen on the occasional kayak or near the island’s coastline.Jellies 1

Left to right: Egg Yolk Jelly, Pacific Sea Nettles, and Moon Jellies

Photo credit: Alyssa Bjorkquist

True jellies alternate between different body shapes and lifestyles throughout their short lives. They tend to take on the characteristic free-swimming medusa form as sexually mature adults and settle down as static polyps during development. True jellies are characterized as plankton for most of their lives, meaning that they are weak swimmers and generally drift with the ocean’s currents. Many true jellies migrate vertically in the water column at night by using rudimentary light-sensitive cells to guide them away from the sun. It is very difficult to pinpoint a jelly’s location at any time due to variability in environmental conditions (ocean temperatures, storms, El Niño events, currents/eddies, etc.) and rapidly changing oceanic conditions from global climate change. However, their planktonic lifestyle has them typically puts them in more open waters away from kelp forests or intense surge around rocky coastlines. Good news for our curious snorkelers!


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Jellies alternate between static polyps or floating medusa in their short lifecycle. 

Photo credit: L. Bornnofft (1995)

Tentacles, oral arms, or a combination thereof are filled with stinging cells called cnematocysts that capture prey and guide it towards the oral opening. Some cnematocysts are powerful enough to register pain when it comes into contact with human skin so it is wise not to touch a jelly, even when it appears dead or washes up onto a beach. (Tip: a vinegar rinse is the medically-recommended way to alleviate a jellyfish sting…not urine. That’s just gross and scientifically incorrect.)


Jellies are critical indicators of environmental health and are an important food source for turtles, some species of fish, and other jellies! Blooms of jellies resulting from pollution runoff and plastic bag presence in the ocean are causing jelly populations to get a bad reputation instead of a graceful example of animal development and hydrodynamic efficiency at a molecular level. Too many jellies in a particular region can shut down boat traffic and create harmful environments for other organisms around them. Furthermore, marine projects researching the effects of ocean pollution are estimating that 83% of sea turtle species worldwide have plastic in their bellies due to their unfortunate physical similarities. Despite their basic appearance, jellies are critical for maintaining an environment’s health and can be a bold sign that something is not how it should be. So next time you see a jelly, wish it good vibes in its eternal drifting life and appreciate their respectful environmental dance from a distance.

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Many animals, including sea turtles, confuse jellies for plastic bags and suffer as a result.

Photo credit: Kelly Fong

DIY jelly crafts recycled from plastic and paper:

  1. Jelly on a stick: http://casahaus.blogspot.com/2010/09/make-your-own-jellyfish-tutorial.html
  2. Paper bowl jelly: http://www.firstpalette.com/Craft_themes/Animals/paperbowljellyfish/paperbowljellyfish.html
  3. Plastic bag jelly: http://www.pbs.org/parents/crafts-for-kids/jellyfish-craft/

To learn more about cnidarians and watch them swimming live, visit these online exhibits:

  1. Aquarium of the Pacific: http://www.aquariumofpacific.org/exhibits/jellies/what_is_a_sea_jelly
  2. Monterey Bay Aquarium: https://www.montereybayaquarium.org/animal-guide/invertebrates/jellies

Check out this article to learn more about the evolutionary history of jellies: https://www.sciencedaily.com/releases/2017/04/170410123957.htm


  1. Purple-Striped Jelly: https://www.montereybayaquarium.org/-/m/images/animal-guide/invertebrates/purple-striped-jelly-upclose.jpg?bc=white&h=800&mh=916&mw=1222&w=1064&usecustomfunctions=1&cropx=86&cropy=0
  2. Moon Jelly life cycle: http://1.bp.blogspot.com/-Msr4i1jY99k/TrAXAJOhfnI/AAAAAAAAAK8/8qXOkOvkNuU/s640/jelly+life+cycle.JPG
  3. Plastic bag vs jelly: https://img.haikudeck.com/mg/35207C43-5098-4877-9F0B-C9BBEF99201D.jpg

Sponges 101

Orange Puffball Sponge // Tethya aurantia

Even though sponges you may have seen while at CIMI are the simplest of the multicellular animals, unable to move (something scientists call sessile), and look nothing like your favorite Krusty Krab frycook, they are actually quite interesting and very important to our marine ecosystems.

Because these animals do not have mouths and do not move, they instead use pores along the outside of their body to filter feed. These pores, called ostia, are where water enters the animal, carrying oxygen and small food particles like algae, protozoans, detritus, and other dissolved organic material along with it. The water is able to move because of hair-like parts called flagella that whip and create a current travelling through the sponge. Once the organism has absorbed the food and oxygen needed, it then ‘exhales’ the water through a larger opening, called an oscula, on its top side. Many sponges also rely upon relationships with photosynthetic organisms to get additional nutrients!

Not only do sponges lack mouths, but they also lack any organs or tissues! Their body is only a collection of almost entirely independent cells. What is even more interesting is what happens when these cells are separated. If the sponge is damaged and these cells are broken apart, the sponge can actually reform, finding and reassembling all of the similar cells until it is whole again! They are the only animals known to be able to do so.

Beyond their unique feeding method and cell structure, sponges are also very important in Southern Californian ecosystems as a food source for many of our favorite sea creatures like sea stars, turtles, sea slugs, and even some fishes!

Written By: Alex Krowiak


Copepods Galore!

What is plankton? And what is a copepod!? Plankton refers to a group of organisms that are not able to swim against the current. The word plankton comes from the Greek word planktos, which means wanderer or drifter. These organisms are composed of plant-like plankton called phytoplankton, and animal plankton called zooplankton. They are the foundation for the food chain in the ocean as phytoplankton contribute a great deal of oxygen during photosynthesis, and zooplankton are a major food source for other animals.

You might be more familiar with copepods than you think! If you have ever seen Spongebob Squarepants, the character Plankton is actually based on a copepod. These one-eyed crustaceans have long antennae and an exoskeleton (skeleton on the outside of its body) and are virtually transparent. The word copepod comes from the Greek kope- meaning oar, and poda- meaning foot, “oar-footed,” because of how the swimming legs of the copepod move together. While there are said to be up to 13,000 species of copepods, they can range in size from .2mm up to 10mm in length. They are the most plentiful multi-celled animals in water and species thrive in extreme water temperatures and altitudes, from freshwater, to benthic to ocean environments. The planktonic marine copepods are a type of zooplankton called a holoplankton, which means that they stay planktonic for their entire life.

It is also believed that about half of the species of copepods are parasitic, and use bony fish, sharks, marine mammals, and invertebrates as a host. To avoid predation, copepods vertically migrate through the water column and sink deeper into the water during the day, but will come closer to the surface at night to feed. Copepods mostly feed on phytoplankton, but some larger species will feed on smaller species of zooplankton. Copepods are even thought to help control human diseases like malaria because they eat mosquito larvae.

Copepods are a major source of protein for our ocean animals, and therefore are a chief contributor to ocean stability. Because they are common plankton in the ocean, they are sure to turn up when collecting a plankton sample, and so fun to look at under the microscope!

Written By: Jaclyn Lucas

Hydrometers: Measuring Oceans Salinity

Hydrometers are used to measure the oceans salinity, or how “salty” the ocean is. To use a hydrometer you must fill up the tool with saltwater and then observe how much the lever is raised by the salinity. We like to use the measurement PPT or Parts per Thousand. PPT is a measure of salinity in the units of thousands, for instance if we had 1000 buckets of freshwater and then added 1 bucket of salt water to it we would have 1 PPT. Here on Catalina Island our PPT ranges from around 32 and 34 PPT. To make more sense of these numbers we like to break them down into percentages. If we were to do that our PPT in percentages would range from about 3.2 to 3.4 percent salt!


There are many other tools we can use to study Oceanography. We will use Secchi Disks to measure the visibility of the ocean, lead lines to measure the depth and plankton tows to measure what exactly is in our water column! Plankton tows work by towing a net with a jar attached to the bottom. The net will siphon through the excess water not allowing the plankton to escape. At the end hopefully you will have a jar full of microscopic plankton!

Plankton Tow

Plankton Tows are a great Oceanographic tool used to sample the microscopic life in the ocean. A jar is attached to the end of the net, while the two are pulled by a boat or dingy. In order to increase the amount of plankton in the jar, a longer tow is suggested. As the tow is pulled through the water excess water will exit through the mesh netting while the plankton is trapped into the jar at the end. To examine these microscopic organisms, you will need a microscope!

Depending on the size of the mesh netting you will collect different types of plankton. Large mesh netting will only collect large zooplankton (animal plankton), while smaller netting will allow you to collect not only those large zooplankton but also phytoplankton (plant-like plankton)! Here at CIMI we use the smallest mesh netting possible to allow students to see both zoo and phytoplankton. After examining you plankton sample you may be able to tell what ocean organisms are reproducing, or how the ocean’s temperature or currents are behaving.



Meroplankton vs. Holoplankton

Meroplankton vs. Holoplankton! In the diverse and unseen world of plankton, scientists have found that all of the zooplankton fall into one of two categories.  The first group is called holoplankton.  Combining the Greek words of “holo” meaning whole or entire and “plankt” meaning drifter, these zooplankton spend their entire lives drifting through the epi- and meso- pelagic zones.  These organisms can range in size from tiny but abundant copepods to the extremely large gelatinous cnidarians such as sea jellies and siphonophores.  These animals are incredibly important food source for both small fish such as mackerel and sardines as well as some of the largest baleen whales.

The second group is called meroplankton.  This name comes from the Greek terms “mero” meaning part and “plankt” meaning drifter.  This group of organisms begins life drifting throughout the sea until they grow and mature enough to settle in another area.  This adaptation allows many of our favorite invertebrates to colonize vast areas of sea floor and prevents competition between parents and offspring.

Bioluminescence in the Ocean

Bioluminescent organisms can create their own light! There are many weird and wonderful bioluminescent creatures in the ocean. Some emit light as a predatory tactic, like the anglerfish, which has a light-emitting photophore that protrudes from the top of its head. The anglerfish has a symbiotic relationship with bioluminescent bacteria that collect on the photophore and help lure prey towards the fish’s mouth. This is helpful in the darkness of the deep sea where food is scarce and hard to find.

Other organisms use bioluminescence to defend themselves. Dinoflagellates are a type of phytoplankton that flash a blue-green light when they get agitated by waves or predators at nighttime. This light can startle and distract the phytoplankton’s predators, or it can act as a burglar alarm that attracts bigger predators to come to the feeding site. Sperm whales are known to linger around places with lots of these bioluminescent organisms because their glowing alerts the whale that there is prey in the area.

Next time you are by the ocean at nighttime, try splashing around in the water and see if these dinoflagellates will light up for you!

What is Plankton Anyway?

Plankton means “drifters” or “floaters.” Many people assume that all plankton are small, however the word does not refer to the size of an organism, but rather how they move around in the water.  One example of a type of plankton that is not well known is a jelly (“jellyfish”, but they’re not really fish).  These plankton can be as large as 6 ft and have tentacles over 100 ft long.  Plankton, like these jellies, are still able to move in the water but have no control over where they go.

There are two main types of plankton, phytoplankton and zooplankton.  Phytoplankton are plant plankton and are often much smaller than most zooplankton.   Zooplankton are animal plankton and are usually larger than other phytoplankton.  Depending on the species, Zooplankton either eat phytoplankton, or even other zooplankton.  Many other creatures including juvenile fish rely on phytoplankton as a source of food.  In fact, plankton as a whole, represent the base of the food chain in the ocean.


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