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Project Lab 

October 2, 2013

Specimen of the Day: Song Sparrow (Melospiza melodia)

Today in the Project Lab, I prepared a study skin of a Song Sparrow (Melospiza melodia).  Although not as prominent as their other sparrow contemporaries, I often hear Song Sparrows speaking to each other in Golden Gate Park through series of “barks,” saying “here I am” and “where are you?”  These small birds can be identified by their streaked breast with central dark spot and heavy malar stripe.  As I walk to work, I start to wonder what interesting things can be learned from this bird.  What in our collections can help us understand more about Song Sparrows?

Slide2

 

The International Union for Conservation of Nature (IUCN) currently classifies the Song Sparrow as a species of “least concern.”  Species in this category are seen as stable populations that presently do not fit into the threatened or extinct category.  Although they are a species of “least concern,” it doesn’t mean they don’t face fierce competition from other birds.  Song Sparrows can be victim of brood parasitism, which is when one bird species lays their eggs in other bird species’ nests.  So how does this happen, and why?

Bird nests come in a wide spectrum of shapes, sizes and materials.  Some birds build completely enclosed nests and other birds lay their eggs directly onto the ground.  Song Sparrows are open cup nesters, meaning their nests look like a cup or a bowl.  Eggs are laid at the bottom of the “cup” and the parent provides warmth and cover by sitting inside the nest.  When these nests are left unattended, brood parasites can swoop in and place their own eggs into the exposed nest.

Insert photo of nests.

Slide1

Brown-headed Cowbirds (Molothrus ater) will lay their eggs in nests of Song Sparrows when the moment is right.  Both lay eggs that look very similar, which may be an adaptation that allows brood parasites to deceive the host.  For Song Sparrows, sometimes the egg is noticed right away and the parent will kick the Cowbird egg out of the nest, but other times the parent will unwittingly raise the Cowbird chick, occasionally to the detriment of its own young.  The Cowbird adult is effectively relieved of parental duties and can invest energy into foraging and breeding, rather than nest building and raising young.

Brood parasitism is seen in cuckoos, some ducks, and a few different passerines. There are many theories as to how this strategy has arisen over time.  The relationship between the brood parasite and its host can be complicated, constantly evolving with one trying to outwit the other.  Song Sparrows and Brown-headed Cowbirds are only one example of this fascinating phenomenon.  Eggs and nests here in the Academy’s collection can be used to study brood parasitism and how it evolves over time.  How much of a role does egg mimicry play?  How much of a role does nest shape play?  These are questions that can utilize the amazing egg and nest collection right here in our very own museum.

 

Codie Otte

Curatorial Assistant and Specimen Preparator

Ornithology & Mammalogy Department


Filed under: Uncategorized — project_lab @ 10:00 am

September 25, 2013

Sea Otter Awareness Week

This week happens to be the 11th annual Sea Otter Awareness Week (September 22nd to 28th). To celebrate, I figured I’d take a break from writing about marine invertebrates and write about this very charismatic marine mammal.    This week in the Project Lab we have a display of sea otter specimens including some skulls, pelts and study skins, so if you are at the Academy, stop by and check it out!

Growing up, sea otters were one of my favorite animals.  I remember seeing them at the Seattle Aquarium as a kid and thinking they were just adorable.  I mean, who could resist a face like this??

Sea_otter_cropped.2

Sea otters (Enhydra lutris) belong to the order Carnivora, which includes mostly carnivorous (and some omnivorous) mammals.  Within the carnivorans, sea otters belong to the family Mustelidae, which includes otters, badgers, weasels and others.  In layman’s terms, sea otters are cute marine weasels!  The species is subdivided into three subspecies:  the Southern Sea Otter (Enhydra lutris nereis), the Northern Sea Otter (Enhydra lutris kenyoni), and the Northern Sea Otter (Enhydra lutris lutris).  Each subspecies has its own distribution, as you can see in the figure below.

special_spp_otter_fig1.3

 

Sea otters live in marine habitats and can be found in protected bays, tidal estuaries and outer coasts, usually associated with kelp beds.  They range from 1-1.5m (3ft 3in- 5ft) long with the males larger than the females.  Unlike seals, sea lions, and whales, these marine mammals don’t depend on blubber to keep them warm.  Instead, sea otters rely on their thick fur that has up to one million hairs per square inch— the densest fur of any animal!    As a comparison, humans have a density of roughly 1000 hairs per square inch on their heads.

 

purple urchin

 

As you can imagine, sea otters are big fans of seafood.  They eat over 100 different prey items including a variety of marine invertebrates (turns out I’m writing about them after all!), such as sea urchins, clams, mussels, abalone and crustaceans.  In order to harvest and prepare their meals, they use tools such as stones to pry food off of rocks or to open up shells.  Interestingly, sea otters that specialize on purple sea urchins will have purple teeth and bones.  If you look closely at one of our specimens on display, you can actually see the purple coloration!

 

 

purple teeth

 

Sea otters are important members of kelp forest ecosystems.   Kelp provides a habitat and nutrients to many organisms, and sea otters play an important role keeping kelp healthy by feeding on kelp predators.   Sea otters are often referred to as a “keystone species” because if they are absent, this can have huge effects on these ecosystems, including too many kelp predators and a loss of kelp and kelp forests.

 

Sea Otter threats

Beginning in the late 1700s, Southern sea otters were harvested commercially, reducing the population in California from about 16,000 animals to the verge of extinction.    All of the current California sea otters are descendants of a small colony of 50 animals from the Big Sur Coast in the 1930’s.  Today, the Southern sea otter is listed as Threatened under the U.S. Endangered Species Act and protected by the California Department of Fish and Game.  The biggest threats faced by sea otters today include oil spills and diseases.  Oil can interfere with the ability of the fur to keep these animals warm.  It can also cause harm through ingestion or fumes.  Diseases are another threat to sea otters and can be strongly influenced by human activities on land.  For example, sea otters are susceptible to a parasite (Toxoplasma gondii) that breeds in cats.  This parasite can enter waterways when cat litter is disposed of improperly by flushing down the toilet.

 

If you are interested in helping sea otters, you can help by:

  • supporting efforts to control urban, industrial and agricultural runoff,
  • supporting efforts to minimize bycatch of marine mammals in fishing nets
  • supporting non-profits involved in sea otter recovery and research, such as the Academy.

 

Here at the Academy, we have the world’s largest collection of Southern sea otter research specimens, which are used by researchers to study these charismatic and important animals.   For the duration of Sea Otter Awareness week, you can see some of these specimens on display at the Project Lab.  Also, as a special treat, you can view sea otter skulls being prepared in the Project Lab and talk to biologists at a special sea otter table during NightLife on September 26 between 6:00-10:00 pm (for ages 21 and over).

 

To learn more about sea otters and Sea Otter Awareness Week, visit http://www.seaotterweek.org/.

 

That’s all for now!

Vanessa Knutson

Project Lab Coordinator

 



Filed under: Uncategorized — project_lab @ 4:32 pm

September 18, 2013

A Threatened Species

Codie last wrote about the effects that plastics can have on bird species. As we all know, there are many more ways that we can have negative impacts on animals of all shapes and sizes. I recently prepared a study skin of a Western Snowy Plover (Charadrius nivosus nivosus), a bird you might be familiar with if you frequent the California beaches that they breed on.

 plovers_photo1 copy

The Western Snowy Plover is a small shorebird that nests and raises its young on beaches. Between the months of March and September, beaches along the Pacific Coast become the territory on which these birds find a mate, establish a nesting site, lay and incubate their eggs, and raise their young. Beaches are obviously a very important part of the life cycle of this species. As we all know, beaches are also important to another species: humans! We use beaches for recreation both for ourselves and our dogs. Between human recreation, urbanization, and the introduction of invasive plant species, suitable beach habitat for Snowy Plovers to breed on has diminished.

plovers_photo2 copy

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What does this mean for the plovers? As you might imagine, habitat loss means less area on which to successfully breed. Even in areas where plovers still nest, humans, predators, and other animals scare adult birds away from their nests, leaving eggs and young vulnerable. This inability to breed can lead to endangerment of a species and, in the worst case, extinction. The Western Snowy Plover has been listed as a threatened species under the Endangered Species Act since 1993, meaning that the species is likely to become endangered within the foreseeable future (endangered meaning that the species is in danger of extinction throughout all or a significant portion of its range). It’s obvious that we need to find a way to allow these birds to breed while still being able to use beaches ourselves.

There have been and continue to be many restoration projects along the Pacific Coast that focus on removing invasive plant species, restoring native plant species that attract beach-dwelling animals, and setting aside protected areas where humans and dogs can’t impact breeding birds. These kinds of projects are crucial to species’ survival!

 

plovers_photo4 copy

 

Am I suggesting that we all keep ourselves and our dogs off of beaches? Absolutely not! I’ve lived the majority of my life in California and love going to the beach (with my dog, as well). We just all need to make sure that we share the beach with native plants and animals. That may mean paying attention to signs pointing out sensitive areas, keeping our dogs on leash, and keeping our beaches clean. It’s a small price to pay to ensure that Western Snowy Plovers, as well as other species, get a chance to survive.

 

Laura Wilkinson

Curatorial Assistant and Specimen Preparator

Ornithology & Mammalogy


Filed under: Uncategorized — project_lab @ 11:01 am

September 12, 2013

They call me Melo yellow…

Most weeks I write about my research subjects: nudibranchs.  This week I thought I’d learn something new and write about some shelled marine snails.

One of the highlights of my trip to Papua New Guinea last year was finding the largest live snail that I’ve ever seen in my life.  I found the snail on a night dive while looking for nudibranchs.   As I approached a large structure, a coral head or perhaps it was a coral-covered boulder, I remember seeing a snail nearly the size of a football.  It was brown in color and its foot was spread out from under its shell like a thick carpet as it moved up the side of the structure.  I remember being overwhelmed with excitement having come across such a large snail, especially as I was looking over sand grains in search of slugs the length of grains of rice!  I immediately decided to collect this live snail, since I couldn’t recall anyone collecting anything quite like this yet on our biodiversity survey.  I grabbed it by the shell and placed it in my catch bag.  It took up a majority of the space in the bag and added a fair amount of weight!

 

Melo in hand cap

While diving in in the field, our team had an in-house competition on each dive to see who could find the most interesting or beautiful specimen, clearly this time, I had won the “shell of the show.”  When we returned to the lab, everyone was excited to see such a large snail, and I was told that it was a member of the group commonly called “bailer” snails.  Our shelled snail experts identified this particular species as Melo broderipii.

 

Melo is a genus of snails that belongs to the family Volutidae.  Many volutes have large shells and some of the largest shells in this family can be found within the genus Melo.   Some of the shells of certain species can grow to 50 cm (19.7 in) in length!  The common name “bailer” comes from the shape of the shell, which can be used to “bail” out water from boats or canoes.  Members of this group are carnivores and eat other snails and seem to live primarily on a muddy or sandy bottom.  They appear to bury themselves during the day and are active at night.

 

779px-Melo_broderipii_01wcap

An interesting thing I read about Melo snails is that they are capable of producing pearls.  Unlike the pearls that are found in oysters, these pearls are not iridescent because they do not contain nacre, which is what makes other pearls and parts of shells iridescent.  Instead, these pearls are yellow to orange in color and have a sort of “flame” pattern to them. To me, they look very much like marbles!

 

Melo_melo_01_by_Line1wcap1

 

These animals are eaten by humans and the shells sold for a variety of uses.  Apparently, they are sometimes used as horns in ceremonies or as ashtrays.

I never cease to be amazed by the diversity of organisms that live on our planet.  I think I might delve into these snails a bit more…

 

Until next time!

Vanessa Knutson

Project Lab Coordinator

Sources:

http://www.palagems.com/melo_myanmar.htm

http://www.sea-ex.com/fishphotos/baler-shell-commercial-fishery.htm

http://www.sea-ex.com/fishphotos/baler.htm


Filed under: Uncategorized — project_lab @ 12:28 pm

September 4, 2013

Spider Sex!

Why is it that biologists always seem to want to talk about sex?  The answer goes back to our understanding of what a species is, and how biologists can tell if animals are of the same species.  While there is more than one definition for what comprises a species, a general description for animals goes like this: A species is a group of animals normally found together that breed and reproduce, creating offspring the same as the parents, who can also reproduce.  In other words, cows mate with cows and produce more cows that can mate and produce more cows. This generalized biological species concept works well for most animals. For larger and more common animals humans have had plenty of opportunities to see mating take place and watch the resulting birth of offspring. People make babies who grow up to mate and make more baby humans, dogs make dogs, etc.  But here’s the catch… the vast majority of animal life on the planet is generally invisible to us most of the time, because it lives in the ocean, deep underground, or hidden from normal view. In fact, many marine and other organisms have had the males and females described as different species, because they look so different from each other. But most of these animals reproduce sexually, using eggs and sperm, and they must have very specific sperm delivery and fertilization organs. This allows scientists to identify males and females of the same species by carefully examining genitalia, because part “A” has to fit into part “B” for everything to work.  And so it is with spiders.

Aranae of the Hearst Philippines Expedition

Spiders often exhibit sexual dimorphism, where the 2 sexes do not look the same. One example is our California black widow spider, where the female is large with a shiny round black belly with a red hourglass marking, while the male is a tiny brown creature devoid of markings.  While not all spider species have such extreme differences, examining genitalia often provides the final answer in species determination.

 

Salticid_Face.2

All spiders have 8 legs, and in addition they have a pair of pedipalps, small leg-like structures originating close to the mouth.  Male pedipalps are highly modified to act as sperm transfer organs, with a thin tube for containing the sperm, and lots of species-specific spines and projections that allow it to mate only with females of its own species.  Sperm is deposited on a sheet of special silk on the ground, then the male touches the drop, which is sucked up into the tube, and he is ready to find a willing mate.

 

Aranae of the Hearst Philippines Expedition

The female has a sclerotized (hardened) area on her abdomen shaped to allow access only to males of her species. By carefully examining these structures, researchers can often figure out who belongs with whom.

CASENT9031589_Epig2

 (All photos taken by Vic Smith at Project Lab)

Until next time,

Vic Smith

Curatorial assistant and imaging specialist


Filed under: Uncategorized — project_lab @ 10:36 am

August 28, 2013

Faux food

Last week Carissa wrote about the Plastisphere and how it has become a floating habitat for microbes.  But what happens when a larger animal comes into contact with these plastics?  The Laysan Albatross is one species negatively affected by plastics in the oceans.

Laysan Albatross breed on the Hawaiian Islands, with over half breeding on Midway Atoll.  During breeding season it may be hard to walk between all of the nesting seabirds – hundreds of thousands of Laysan Albatross come to Midway Atoll.

Slide1.2

Adults arrive in November to court, mate and lay an egg, and the chick will fledge and leave Midway in July.  This long process means that most birds will only lay one egg per breeding season.  After a few weeks together, the nestling is left alone on the island for the next few months while both parents forage at sea.  Unfortunately an increasing amount of the “food” periodically brought back to these chicks is actually bits of plastic.  The Great Pacific Garbage Patch can be found in the same area that Laysan Albatross forage for food and these plastics are making their way back to land in the stomachs of birds.

Why would a bird intentionally ingest plastic?  Albatross primarily eat invertebrates such as squid and jellyfish and shredded plastic bottles floating on the water can resemble either of these foods.  Plastic of various colors and sizes are mistaken for other marine invertebrates as well, and scooping up the pieces the Albatross fly back to Midway and feed it to their young.  Many nestling Albatross are unable to survive due to malnutrition or punctured stomachs from the plastic they are fed.

Slide2.2

Although not currently considered a threatened species, over time this could

become problematic for the Laysan Albatross population as a whole.  If each pair is only laying one egg a year and that chick dies before leaving the nest the number of chicks replacing older adults could dwindle.

Plastic ingestion is a scary thought, but even when it is not being incidentally eaten, plastic can still affect birds through entanglement.  Plastic entanglement is a problem not only on Midway Atoll, but even closer to home here in San Francisco.

Slide3.2

 

This Common Murre (Uria aalge) was found on Ocean Beach caught up in netting.  The netting has actually wrapped itself around the wings and feet in such a way that the bird would not have been able to fly or walk.  I prepared the bird as a study skin to have a record of the way plastics can negatively impact our avian community.  Many animals can have limbs or even necks caught in plastic bottles, plastic rings that hold soda cans or even plastic bags.

While San Francisco has already banned plastic bags, there are many other items that we throw away or recycle that can accidentally end up in the ocean.  Unless you already have your next arts and crafts project mapped out, it’s always good to pause and think about whether you need that extra packaging or plastic bottle.  Sometimes plastic can be “reused” in ways we had not anticipated!

 

Codie Otte

Curatorial Assistant and Specimen Preparator

Ornithology & Mammalogy Department


Filed under: Uncategorized — project_lab @ 10:25 am

August 21, 2013

The Plastisphere- an artificial marine ecosystem

This week I attended the event Women in Ocean Science at the Aquarium of the Bay. Here I learned about the plastisphere, an ecosystem of marine microbes living on plastic floating in the ocean. How trash is dealt with has always intrigued me. When I see mounds of garbage on the streets and beaches of San Francisco I become disgusted. Some of this garbage makes its way to the Great Pacific Garbage patch, estimated to be about twice the size of Texas! About 4.7 million tons of garbage enters the world’s ocean in a year, which contribute to the five trash gyres found in the oceans.  If we do not clean up our act, the ocean will one day be a giant plastic soup!

Image 2

The plastisphere is extremely biodiverse. Plastic collected in the North Atlantic contained 50 species of single- celled plants, animals, and bacteria comprised of photo-synthesizers, herbivores, predators, and decomposers. Another study discovered 1,000 different kinds of microbes on a piece of plastic only about 5 mm across.

Plastics are energy rich substances consumed by some species of terrestrial bacteria and fungi. The marine microbes living on floating plastic may also be capable of breaking down plastics. Electron microscope images of bacteria living on plastic surfaces have shown spherical pits surrounding the bacteria. More research needs to be done to substantiate this claim. Despite this, plastics in our oceans will not be able to be degraded at the rate at which plastics are entering the ocean.

Photo 1

Overall, the plastisphere is bad news for natural marine ecosystems. The microbes in the plastisphere may use up phosphorus and strip it away from other marine organisms. In addition, the plastisphere could serve as a source for human disease transmission since fish and shellfish ingest tiny pieces of plastic harboring Vibrio and cholera-like bacteria, which cause food-born illnesses. Finally, plastics may also transport microbes long distances leading to more occurrences of invasive species.

On a more positive note, the plastisphere may possess non-harmful bacteria containing compounds useful for drug discovery. It is an extremely interesting artificial biosphere since it harbors a vast diversity of microbes and illustrates the amazing adaptability of nature! It is an entirely new ecosystem awaiting scientific discovery.

 

Stay tuned for next week’s post on plastics and albatross.

 

Carissa Shipman

Graduate Assistant in Public Programs

Invertebrate Zoology and Geology


Filed under: Uncategorized — project_lab @ 12:23 pm

August 15, 2013

Numbering skeletons

Recently, I’ve been working in the Project Lab on a different kind of task than usual: numbering bird and mammal skeletons. While I’m usually busy preparing research specimens for our collections, there are other steps that bridge the time a specimen is prepared to the time that it can be integrated into our collection. With study skins, this involves allowing the skin to dry, freezing it (to kill off any pests that may have hitched a ride during the preparation process), cataloging it (giving it a number that identifies it in our collection), and then integrating it into the collection. Skeletons, however, require the additional step of having each bone numbered after the specimen is cataloged.

I commonly get the question of whether I put a different number on each bone to identify what bone that is, helping to make putting the skeleton back together easier. The answer is: no! The number that goes on the bones is the same for each bone and is the specimen’s catalog number – its unique identification number within our system. We also keep our skeletons disarticulated, or not put together. This makes it easier for researchers to look at specific bones. For instance, if a researcher brought in a vertebra (part of the back bone) from a mystery animal and wanted to identify it by comparing it to skeletons in our collection, it would be much easier for them to compare all of the details of the bone if the skeletons were completely disarticulated.

What’s the point of all the numbering? Shouldn’t we be fine as long as we put the number on just one bone in the box? The answer again is: no! Imagine a tray of 50 boxes of skeletons. If that tray fell and each skeleton scattered, how would we know which bone goes with which specimen? This is why we put the catalog number on each bone, with the exception of tiny skeletons where the bones are too thin to write on. In those cases, we write on as many bones as possible.

numbering skeletons_photo1 copy

Similarly, if a skeleton is mostly articulated (the bones are still attached), we still number every single bone. If the skeleton was to fall and the bones separated, we would still need each bone to have its own number.

 

numbering skeletons_photo2 copy

 

Numbering is a slow process, but someone has to do it!

 

Laura Wilkinson

Curatorial Assistant and Specimen Preparator

Ornithology & Mammalogy


Filed under: Uncategorized — project_lab @ 3:55 pm

August 9, 2013

Summer Systematics Institute

Systematics: The study of the evolutionary history and diversity of living things and the relationships among these through time.

This week I decided to write about a great program that we have available to undergraduates within our Institute for Biodiversity Science and Sustainability, called the Summer Systematics Institute (SSI).   This program is partially funded by the National Science Foundation’s Research Experience for Undergraduates (REU)  program and the Academy’s Robert T. Wallace endowment.   It is an 8-week paid internship working with an advisor, usually an Academy curator or post-doc.  This summer, the program is in its 18th year and there are 12 participants from all over the country, including a biological illustrator.   During the 8 weeks, the interns learn new techniques and conduct original research, all while attending a series of lectures on themes related to the field such as phylogenetics, collections management, bioinformatics, morphometrics, nomenclature, and biogeography.

SSI taxa compilation

For the past three summers, I have had the wonderful opportunity of helping students in the molecular lab as the Teaching Assistant in the Center for Comparative Genomics.  In this role, I train students how to extract DNA from their specimens and how to use molecular techniques in order to sequence the DNA from those specimens.   The students then use these data to help answer research questions about the evolutionary histories of species or populations.  Not all interns use DNA data as a part of their projects, but since molecular data is commonly used in our field of biology, this is a great opportunity to either learn new techniques or refine techniques that students may have had some exposure to previously.  This year I was able to train some of the interns in the Project Lab, so if you visited in the last few weeks, you may have seen some of them working on their projects!

Yesterday, after a busy 8 weeks, the program culminated in a day where the students gave scientific presentations on their projects.    This year’s projects were quite impressive, and the students worked very hard.  Below are photos of some of the presentations.

IMG_3717david

IMG_3706Jessica

IMG_3680sarah

IMG_3669Anna

 

To me, the most exciting thing about this program is that the interns get authentic research experience.  I know this to be true because in 2006, I was an SSI intern!  This program really fostered my understanding of and passion for the field of systematics.  If I had not done this program back when I was an undergraduate, I probably wouldn’t be earning a master’s in this field today.  For more information on the SSI program, click here.

 

Til next time!

Vanessa Knutson

Graduate Student, IZG Dept

Project Lab Coordinator


Filed under: Uncategorized — project_lab @ 12:07 pm

August 1, 2013

Of Sea Monkeys and Fairies

Many folks that I have spoken to in the last week remember the enticing advertisements that used to commonly appear in comic books and kid’s publications, promising amazing experiences with the new pet craze, the Sea Monkey aquarium.  Containing a small plastic aquarium, a packet of dried eggs, some food and minerals, and a magnifying glass, “just add water” and soon you would have a flotilla of tiny, shrimp-like creatures rapidly swimming around on their backs, darting hither and yon around your new instant aquarium.  It sounded great to me as a 10 year old, but I never knew anyone who actually had them.

 

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These tiny creatures bear no resemblance to monkeys, but are in fact small crustaceans commonly referred to as brine shrimp when they are found in salt water or hyper-saline pools, or fairy shrimp when they are found in fresh water.

These are not shrimp at all, but belong to the crustacean class Branchiopoda, in the order Anostraca.  Usually between 6 to 25 mm long, they have paired eyes and from 14 to 16 pairs of legs used both for locomotion and to stir up water currents around their gills to aid breathing.

 

CASIZ174264_Lat.tif(high contrast).2

Here in California, fairy shrimp are found in vernal pools, also known as ephemeral ponds. These habitats form for only a few months from about December to May, as low lying areas of wetlands fill with water, which then evaporates leaving the pools dry by summer’s end.  Throughout the U.S., wetlands are an endangered habitat closely regulated by the federal government.  Here in California, many vernal pools are found in the Central Valley, often in agricultural areas and places ripe for development.  The delineation of wetlands on private property often causes controversy and clashes between owners, conservationists and the government.

 

CASIZ174264_FF_Lat.2

 

There are several species found throughout California, but this blog focuses on the California Vernal Pool Fairy Shrimp, Branchinecta lynchi, which is federally listed as a threatened species.  These suspension and filter feeders eat unicellular algae, bacteria, and ciliate protists, and also scrape diatoms, algae and protists off of rocks and twigs.  They are an important food source for migrating birds and other organisms using and visiting the pools.  They exhibit sexual dimorphism (physical differences between the male and female), the smaller female recognizable by the attached egg sac, while the male is bigger and more robust, with a pair of large claspers, which are greatly enlarged second antennae, used in mating.  Females of this species lay two different types of eggs.  Summer eggs are soft, and will hatch within the season. Winter eggs have a tough skin, which allows them to form a cyst as they dry. These encysted eggs can survive in soils and sediments for an amazingly long time, up to 10 years!  Winter eggs can be blown long distances, or carried by birds.  This transport from pool to pool increases genetic diversity, aiding species survival.  Pools with lower genetic diversity are more susceptible.  The prevalence of pesticide usage, filling and paving over of wetland areas, and other human activities are the major threats to populations in California, and elsewhere.

 

The photographs were taken by me with the Big Kahuna digital imaging system, and are voucher specimens from a government survey in the collection of our Invertebrate Zoology department.

 

Until next time,

 

Vic Smith

Digital imaging specialist/Invertebrate biologist


Filed under: Uncategorized — project_lab @ 10:28 am
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