Monday, August 31, 2015

Fresh Water Jellyfish

Craspedacusta sowerbii  - Wikipedia CC
An article in the News-Leader by Francis Skalecky introduced me to fresh water jellyfishCraspedacusta sowerbii is an Asian species of jellyfish accidentally introduced into North America.  According to Freshwaterjellyfish.org - (yes they do have their dedicated website) they are now found in 44 of the lower 48 states.

C. sowerbii jellyfish are small, reaching the diameter of a quarter.  They have typical jellyfish features, an umbrella with stringy tentacles attached to the edges.  These contain cnidocytes, specialized stinging cells which they use to paralyze their prey, macroinvertebrates and small fish.

They are easy to miss as they are somewhat translucent. Their gonads on the underside may be the first thing spotted before making out their overall shape.  Their lifecycle is difficult for me to grasp, involving podocysts, polyps and frequent asexual reproduction explained below.
"A tiny, stalked form of the jellyfish (the polyp) lives as colonies attached to stable underwater surfaces such as rooted plants, rocks, or tree stumps. The microscopic polyp colonies feed and reproduce during the spring and summer months. The polyps reproduce asexually. Some of their offspring are the jellyfish that can be seen at the surface. The "jellyfish" or medusa reproduce sexually. Fertilized eggs develop into planula larvae which eventually settle to the bottom of the pond or lake and develop into polyps. However, in the United States, most populations of jellyfish are either all male or all female, so sexual reproduction may be rare."  Freshwaterjellyfish.org
The polyps contract in winter forming podocysts or resting bodies which may explain how they have spread to isolated ponds and water bodies, possibly transported by aquatic animals and birds.*   They may be suddenly found in large numbers one year with none the following years.  In some cases they have totally disappeared from a lake.

Although they have stinging cells, there are mixed reports on whether they can sting us.  Many people report handling them with no discomfort while others report mild itching and red spots or a slight numbness. Either way, they appear to be nothing to worry about while swimming in Missouri waters.
* Freshwaterjellyfish has a very detailed FAQ including caring for them in an aquarium.  Although not specifically mentioned, this must be a possible way of spreading them by compassionate dumping of aquarium contents. 

Friday, August 28, 2015

Phorid Flies

Phorid fly from our sink
This may be the smallest fly in your house that you have never seen. Occasionally I will see tiny dark insects, 4mm long, darting around in jerky movements in the kitchen sink by the compost container. They were impossible to photograph while darting around, never flying away.  I finally caught one in a small container and tossed it in the freezer - yes, my Master Naturalist live-in editor is extremely tolerant.

Under magnification I was surprised to see one pair of wings typical of the order Diptera, and impressively long legs.  Chris Barnhart identified them for me as flies in the family Phoridae.  They are lovingly referred to as scuttle flies, coffin flies or laboratory flies.  The scuttle refers to their habit of darting around to escape rather than flying away.

As you might guess, many species eat decaying materials including some that can persist in a sealed coffin for long periods of time.  They are commonly found around kitchens, sinks and in laboratories which house research animals.  Many Megaselia species are found feeding on fungi.  The "world's smallest fly", Euryplatea nanaknihali (0.4 mm, the size of a grain of pepper), is a phorid fly. 



The most interesting group is Apocephalus (apo - away from, cephalus - head).  Many of these species are known as ant-decapitating flies.  They will lay their eggs on ants' abdomens.  When their larvae emerge they move up to the head, feeding on it until the ant's head until it falls off, sometimes while the ant continues to move.  On the other hand, members of the genus Dohrniphora actually will bite the ant's head off and haul it off as seen on this video.

While we may not have a lot of sympathy for ants, bees are another matter.  A. borealis lays its eggs on bumblebees and wasps, with the larvae moving into the bee's head.  The parasitized bee has been called a "Zombie Bee" because of its tendency to act crazy and fly at night before dying.  About a week later the flies emerge, decapitating the bee.  Last year attacks on honey bees were confirmed, also documenting the fly can transmit deformed wing virus and Nosema ceranae, suspected factors in Colony Collapse Disorder.

When compared to others of the order Phoridae, our occasional visitors are rather benign.  I guess I will have to learn to put up with them, especially since I am too slow to squish them.

Tuesday, August 25, 2015

Hummingbird Tongue II

Blue-Tailed Hummingbird - Honduras - Courtesy Robert Gallardo
Back in May in Hummingbird Tongue we discussed the new findings of how a hummingbird's tongue worked based on new postmortem studies.  To quote from that report:
"The hummingbird has a forked tongue which is lined with hair-like extensions called lamellae. When inside the flower, the tongue separates and the lamellae extend outward. As the bird pulls its tongue in, the tips come together and the lamellae roll inward. This action traps the nectar within the tongue."
New studies have expanded our knowledge of the physics involved in fueling a hummer, functioning as a tiny elastic pump. Using tiny glass tubes with artificial nectar, researchers made high speed videos of 18 species of hummingbirds in Connecticut, Texas, California, Ecuador, Columbia and Brazil.
"We show that the tongue works as an elastic micropump," the researchers said. "Fluid at the tip is driven into the tongue's grooves by forces resulting from re-expansion of a collapsed section" of the tongue closer to the mouth.  This fast technique allows the bird to drain between five and 10 drops of nectar from a flower within 15 milliseconds (about 100th of a second)," Rico-Guevara told Livescience.com
The part of the mouth closest to the beak expands, drawing in fluid which is then pumped into the throat.  Even more incredible, it involves the tongue structure alone, not involving any muscles or nerves.  Studies like this only make me wonder what we will learn about the physics of bugs that can suck the juice out of a stiff plant stem, or more personally, a mosquito blood out of my skin.

Photograph above is from our friend Robert Gallardo who has written Birds of Honduras.  He guides birders through Honduras which is the winter home of 60 of our Missouri migratory birds, especially warblers.  More information at Birds of Honduras.

Sunday, August 23, 2015

Urban Swifts

Chimney swifts - Richard Crossley CC
We will be posting a lot about chimney swifts over the next year but I felt this issue couldn't wait for the calendar to catch up. 

I am reprinting Jim Fossard's letter to the editor in today's News-Leader as an introduction to the problems that swifts face as we "clean up" downtown Springfield as well as historic structures in all our cities.
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I have been impressed by the development in downtown Springfield, with the “Sky 11” and “The U” loft projects, but one unfortunate, but easily fixable, casualty of this development was the loss of a really great chimney swift tower in the form of a ventilation chimney on the southeast corner of McDaniel Building, now “The U” lofts.

Hundreds of chimney swifts would congregate every evening to roost in that chimney, much to the delight of downtown residents and customers, who would marvel at their acrobatics just as the sun set. Chimney swifts migrate to North America from the Upper Amazon basin, Bolivia and Peru in the spring. Unlike most birds, chimney swifts are unable to perch or stand upright and must have chimneys or similar structures in which to roost and raise their families. As summer draws to a close and the swifts have finished raising their young, these fascinating aerial acrobats begin to congregate in communal roosts prior to their migration in the fall. Some roosts may consist of an extended family group of a half a dozen birds or so, but the larger sites can host hundreds or even thousands of swifts.

Looking around downtown Springfield, there are several capped chimneys that would make excellent habitat for chimney swifts, which are unfortunately in a steep decline in North America because of the lack of chimneys in buildings and homes. It would be wonderful if those chimneys could be uncapped, at least for the warm months of the year. Residents and visitors to the area would really get quite a show during this time of the year and it would be a draw for businesses with visitors who enjoy this aerial display. If you have never seen such a display, you are missing one of the wonders of nature.

Jim Fossard is a member of Greater Ozarks Audubon Society with a special passion for swifts.  More on these projects later.

Saturday, August 22, 2015

Drones and Conservation

Civil Drone FOX-C8-HD AltiGator- Wikipedia
Love them or hate them, drones are a hot topic throughout the world.  There is even a website devoted to the topic, conservationdrones.org.  As with many new drugs, first "it's a miracle cure" but a short time later "it will kill you!"  Now we are finding concerns about the use of drones in wildlife studies.

Drones are now used to monitor seabird populations, monitor elephant habitat, study marine habitat in Belize, and monitor wetlands in Scotland.  The greatest cause of mortality among the US Fish and Wildlife employees is small plane crashes during aral observation missions.  Retired military drones are now sparing their biologists hazardous plane flights while monitoring volcanoes, studying flood zones and tracking endangered wildlife.  In the tropical forests drones patrol to detect illegal logging.

The use of drones to monitor African wildlife and catch poachers has taken off but has attracted controversy.  Engineering and Technology Magazine has a major discussion of the issues including bans by many African governments.

With familiarity comes contempt as we start to recognize the downsides of this new technology.  Airline pilots are not the only mammals frightened by the proliferation of drones, they also bug the bears.

A report in  Discovery.com describes the results of a project which monitors bears.  They were studying bears in northern Minnesota, equipping them with GPS collars and cardiac biologgers capable of reporting their location and heart rate.  They logged 18 flights of five minutes each and noted that the bears did not seem bothered by the drones.  However their monitors showed a different story.
""Some of the spikes in the heart rate of the bears were far beyond what we expected," co-author Mark Ditmer of the University of Minnesota, St. Paul, said in a press release. "We had one bear increase her heart rate by approximately 400 percent -- from 41 beats per minute to 162 beats per minute. Keep in mind this was the strongest response we saw, but it was shocking nonetheless."
Another thing that bugs bears are ticks.  We have seen ticks on bears which have been trapped for collaring but now MDC is studying the tick burden in different seasons.  The initial summertime counts have gone from 200 to 1000!  That gives a whole new meaning to "ticked off."

Count the small white dots of engorged ticks
Some years back we had the opportunity to drift over elephants in a hot air balloon over the Serengeti.  These gentle giants were able to walk within a few feet of a Range Rover full of camera laden tourists but our balloon 100 feet overhead caused them to panic, trumpeting and breaking into a run.  Although they were the largest animals, seemingly oblivious to a wide variety of predators, a new threat from above spooked them.  We assume that wildlife ignores our aerial surveillance by planes and drones.  It seems that we have a lot to learn about wildlife.

Monday, August 17, 2015

Long-bodied Cellar Spider

Spreading out on the wall - REK
After years of watching these leggy spiders crawl all over the bathroom in our creek house, I thought it was time to give them their day in the sun.  After all they spend the rest of their lives sequestered in dark, damp places asking for nothing and bothering no one, unless it is a house guest too polite to mention them.  For the most part they just hang on a wall or slowly explore the tile floor, looking for tiny pests that we don't even know exist.

This is the Long-bodied Cellar Spider, Pholcus phalangioides, the most common of the Pholcidae or cellar spiders.  They have a number of common names including daddy long-legs spider, granddaddy long-legs spider, carpenter spider, and vibrating spider. Their bodies are 5-8 mm long, (less than 1/3") and their leg are 8 times longer.

"Daddy Longlegs" Crane Fly- Six legs of an insect  - REK
Crane fly - Limonia - REK
Their "daddy long-legs" name is appropriate but can be confusing.  This common name is also applied to both harvestmen of the Opilione class and to crane flies which are sometimes mistaken for giant mosquitoes.  Crane flies have 6 legs like all insects and wings typical of all the Diptera (true flies).


Long-bodied spiders have three distinct body parts (head, thorax and abdomen) while the Opiliones (harvestmen) have the head and thorax fused into one small part frequently making their bodies appear oval.  Both have eight legs typical of the Arachnids.

Harvestman - REK
Long-bodied Cellar Spider - REK
They originated in the sub-tropics but are now found on every continent, probably traveling along with the commerce of humans.  They do not tolerate cold but have found their niche in warm human habitats.  In their original lands they reproduce annually in the warm season while in our house it is always the season to reproduce and life is good.

Skull shaped head with two sets of three round eyes tightly clustered together - REK
Because of the shape of their thorax they are also commonly called a "skull spider."  Another defining characteristic of various spider species is the placement of their eyes.  In this case there is a set of three round raised eyes clustered on both sides of the head as well as another pair in front.

Female with egg case - Olei CC- Wikimedia
A female produces 20-30 eggs which she will patiently carry around in her pedipalps until the young hatch.  The young will molt six times before they reach maturity

Mother and babies - Luis Fernández García via Wikipedia
Their webs are irregular, messy but very small, tending to cling to a wall or other horizontal surface.  When they perceive a threat they start vibrating on their web, making them harder to see, thus the "vibrating spider" name.

Long-bodied spiders have very weak venom and are barely able to pierce human skin, with only a temporary discomfort.  On the other hand, they are considered beneficial as they are predators of many venomous spiders that are threats to us.  As we see an occasional brown recluse in the nooks and crannies, letting these leggy creatures patrol the house is a small price to pay.

Sunday, August 16, 2015

Milkweed Bugs



We had a colony of Large Milkweed Bugs covering a small cluster of milkweed.  They are not a serious threat to the plants in general but this plant was being saved as a source for seeds.  I received permission from my editor to study them for several days before they were removed.

As you might guess by the name, Large Milkweed Bug, Oncopeltus fasciatus, there is also a Small Milkweed Bug which we observed in upstate New York recently.  Both have the bright orange aposematic coloration warning that says "I am full of milkweed toxin- consume at your own risk."

Small Milkweed Bug
Large Milkweed Bug


All five instars of nymphs clustered together
"The milkweed bug undergoes incomplete metamorphosis. The nymphs look like adults but do not have full wings and their color pattern is different. They have five instars before they reach adulthood. Black wing pads appear early in their development. Eggs are a light lemon yellow changing to a reddish color. Incubation period is about four to five days. Each molt lasts five to six days. An adult will live for about one month. The insect overwinters as an adult." Missouribotanicalgarden.org


Milkweed bugs suck the liquid from the plants using their long proboscis which extends down along the abdomen.  The toxic chemical they ingest from milkweed is transmitted into the eggs. They are extremely productive, laying 30 eggs a day and up to 2,000 in their lifetime.  This trait makes them ideal subjects for insect laboratory research because they also have a short life cycle and are easy to manipulate.








 

There are several subtle (to me) anatomical differences between the male and female.  The easiest way to tell is to compare a mating pair, because the female tends to be larger than the male. Since copulation lasts for up to 10 hours there are usually multiple pairs on a single plant. 

The large milkweed bug, Oncopeltus fasciatus, is a good species to study for an understanding of hemiptera ("true bugs").  They are said to be easy to raise with a short life span, making them the perfect "lab rat" for an entomologist or a classroom full of 5th graders.  They can be fed cracked sunflower or watermelon seeds.*  That said, I followed the directions carefully and all of mine went on a hunger strike and died.  Obviously I am not up to the 5th grade level.

* Instructions for raising milkweed bugs are available at this link.

A "must watch" video from Cornell discusses how Monarch caterpillars handle milkweed defenses.