Snail Tales

Snails and slugs crawl at a speed of .006-.03 miles per hour- what could a creature so slow even be good for? Most of our lives move too fast to pay them much attention, but they make a whole other world at our feet; approximately 40,000 different species (very slowly) roam the earth!

The class Gastropoda, including slugs, snails, limpets, sea hares and sea butterflies, belongs to the phylum Mollusca, classified as soft-bodied animals bearing an external shell (although many animals without shells belong to Gastropoda). There are approximately 150,000 different species on earth! Gastropods are the largest group of mollusks, and as such it is difficult to pinpoint or characterize the life history of any one species. They have been in existence for approximately 480 million years dating back to the Cambrian era; fossils are easily preserved due to their shells being made of a hard calcareous material that holds together well over time.

 

Gastropod fossils.

Fossils of Nerinea marine gastropods of late Cretaceous (Cenomanian) age, in limestone in Lebanon. Photo by Laurence Comte.

 

Gastropod means “stomach foot,” relating to Gastropoda’s unusual anatomy; in their mature larval stage, they undergo torsion, a process that repositions their organs near their head, including the stomach. Their foot- you guessed it- resides where their stomach once was! It is a muscle that expands and contracts to allow movement.

 

Internal anatomy of a snail.

The anatomy of a common air-breathing land snail. Note that much of this anatomy does not apply to gastropods in other clades or groups. Diagram from Wikipedia.

 

They are most commonly either herbivores or scavengers, feeding on dead animal matter and plant material such as leaves, stems, and algae. Certain species are known to be carnivorous and prey upon other smaller invertebrates. Being so diverse, gastropods can be found in nearly any habitat; both in saltwater and freshwater, on land in marshes, forests, mountains, and even deserts, at almost all altitudes and latitudes. Due to such a wide range, specific choices of sustenance per species are a wildcard.

One of Gastropoda’s most defining characteristics is their “slime trails.” This mucus is released by glands on the sole of their singular “foot” that makes up the whole underside of their body, alleviating friction between the sole and the ground. It is even possible for certain gastropods to crawl along a knife’s edge unscathed! This muscular foot is characteristic of nearly all gastropods.

 

Slime trail.

Remnants of a slime trail on asphalt. Photo by Hans Braxmeier.

 

Gastropoda’s other most obvious and unique trait (pertaining to only some species) is the shell. The pattern of the shell is usually coiled and can be sinistral (spiraling counter-clockwise) or dextral (spiraling clockwise). It is created by a cell layer located along the rim of the shell mouth that secretes calcareous matter (meaning mostly or partly comprised of calcium carbonate) which will then harden into a prism or plate crystals. In this way, the shell grows in size as it grows in thickness (talk about DIY homes!). Gastropods will withdraw into this shell to avoid predators or conserve water.

Many gastropods are hermaphrodites, meaning they bear both male and female reproductive organs, which are usually located near the head; however, not all are capable of self-fertilization. Most gastropods reproduce sexually, yet the method of copulation is greatly dependent on their environment. Some fertilize their eggs outside of the body in water, others penetrate their mate with “love darts” (don’t worry- they don’t hurt!). Leopard slugs, depicted in the below image, have got it twisted-literally. After an inexplicable circling ritual, they hang from a branch using mucus as a lifeline; that translucent knotted substance is their penises exchanging sperm, which will then fertilize the eggs in their respective female reproductive structures. These reproductive knots have often been seen to “flower” or “bloom”. How beautiful…There have even been observed species, such as the slipper limpet (Crepidula fornicata) that can undergo environmentally mediated sex changes in order to manage a sexually-imbalanced population. For the most part this is a male-to-female transition given that that most organisms of these species have a slightly higher male distribution.

 

Two slugs mating.

Mating of Limax maximus. Photo by T. Hiddessen.

 

“Shell art” is a staple in westernised beach culture- anything from earrings to chandeliers are created from the shells of gastropods (as well as other molluscs). While beautiful and fascinating to be able to observe an otherwise hidden aspect of nature so up-close, shell-collecting is a notoriously unsustainable practice. Shells are used as shelter for algae, material for bird nests, and homes for hermit crabs. Many shells used in shell art come from snails harvested for consumption – an age old practice worldwide – but this too yields environmental consequences when done recklessly. Nonetheless, gastropods are a resilient and biodiverse class of organisms that will continue to amaze us (and gross us out) so long as current global conservation trends continue.

 

By: Tom Gregg

Feature Photo by: Jussi, Flickr

Sources:
Kennedy, J. (2016). Characteristics of the Gastropoda. Retrieved November 09, 2016, from http://marinelife.about.com/od/invertebrates/p/Class-Gastropoda-Snails.htm.
Gastropod – Reproduction and life cycles. Retrieved November 09, 2016, from https://www.britannica.com/animal/gastropod/Reproduction-and-life-cycles.
Gastropoda – slugs and snails. Retrieved November 09, 2016, from http://www.ento.csiro.au/education/allies/gastropoda.html.
Nordsieck, R. Snails and Slugs (Gastropoda). Retrieved November 09, 2016, from http://www.molluscs.at/gastropoda/index.html?/gastropoda/morphology/locomotion.html.
Nordsieck, R. Snails and Slugs (Gastropoda). Retrieved November 09, 2016, from http://www.molluscs.at/gastropoda/index.html?/gastropoda/morphology/shell.html.
Nordsieck, R. Snails and Slugs (Gastropoda). Retrieved November 09, 2016, from http://www.molluscs.at/gastropoda/index.html?/gastropoda/morphology/reproduction.html.
How fast does a slug move per hour? (2000, March 30). Retrieved December 11, 2016, from http://www.madsci.org/posts/archives/2000-03/954420651.Zo.r.html.
The Gastropoda. Retrieved December 11, 2016, from http://www.ucmp.berkeley.edu/taxa/inverts/mollusca/gastropoda.php.
Images:
Jussi (Flickr). Snails. https://www.flickr.com/photos/53434152@N00/14038928588/.
Nérinées dans le Crétacé libanais. (2011, July 11). Retrieved November 09, 2016, from https://www.geodiversite.net/media551.
Gastropoda. Retrieved November 09, 2016, from https://en.wikipedia.org/wiki/Gastropoda.
Free Image on Pixabay – Snail, Slime Trail, Shiny. Retrieved November 09, 2016, from https://pixabay.com/en/snail-slime-trail-shiny-474286/.
Hiddessen, T. (2010, October 7). File:Limax-maximus mating 2.jpg. Retrieved November 9, 2016, from https://commons.wikimedia.org/wiki/File:Limax-maximus_mating_2.jpg.

Mecoptera: First on the Crime Scene

Since the 1960’s, over 200,000 murders have remained unsolved: a shocking rate of 1 out of every 3 cases. An emerging field offers promising new solutions. Forensic entomology helps solve mysteries by examining the types of insects present at a crime scene and the evidence they leave behind on a body or the surrounding area. Insects can provide clues about time of death and location of death, as well as capture important DNA evidence. Previously, forensic entomologists relied heavily on blowflies for data, believing that these insects were the first on the crime scene. However, a new study from forensic entomologists at the Southeast Texas Applied Forensic Science Facility reveals that a different insect (Mecoptera) is actually the first visitor to a newly deceased corpse. This vital information shifts the focus for forensic entomologists and provides valuable information on time of death.

 

The insects, Mecoptera, are commonly known as hangingflies or scorpionflies. Despite these names, scorpionflies are not actually true flies. That group is Diptera, and it includes your common housefly and fruit flies. Scorpionflies received their name because they can fly and they have enlarged sexual organs on males that mimic scorpion tails. Despite the uncanny resemblance to scorpion tail structures, no members of Mecoptera sting or have venom. Mecoptera‘s other common name, the hangingflies, refers to the tendency of Mecoptera to hang under leaves in order to catch prey and to procreate.

 

Male scorpionfly.

A male Mecoptera, or scorpionfly. The enlarged organ at the end mirrors a scorpion’s tail. Photo by Gail Hampshire (Flickr). The female scorpionfly lacks this feature, as you can see in the cover photo of this post. Cover photo by Vlad Proklov (Flickr).

 

The long wings of scorpionflies are one of the defining features of the Order. Almost all members of Mecoptera have four membranous (slightly transparent, soft) wings all roughly equal in size attached to their long body. The head of a Mecoptera is also very distinct and often is described as horse-like. This head contains chewing mouthparts that are used to feed on small insects and decaying animal matter.

 

A scorpionfly and a beetle, highlighting wing differences.

A comparison of the membranous wings of a scorpionfly (Order: Mecoptera) on the left to the hardened top wings of a beetle (Order: Coleptera) on the right. You can see that beetles also have membranous wings under their hardened wings. Photos by Walwyn and Gilles San Martin, respectively (Flickr). The beetle photo has been cropped from the original.

 

Close up of a mecoptera mouth.

The “horse-like” long face of Mecoptera, with mandibular (chewing) mouthparts at the end. Photo by Colin Avison (Flickr).

 

One subset of Mecoptera, Bittacidae, uses their specialized hind legs to catch prey while hanging onto the underside of leaves with their front legs. These hangingflies are actually the only predatory insects worldwide that use their hind legs to capture food. Another subset, Panorpidae, takes a much more opportunistic approach and instead robs spider webs rather than finding and capturing food for themselves.

 

A scorpionfly eating a spider.

A Bittacidae hangingfly capturing prey using its hind legs, while hanging below a branch. Photo by Linda Rogan (Flickr).

 

 

Scorpionfly robbing a spider's web.

A Panorpidae scorpionfly robs a spider web for food. Photo by Ferran Pestaña (Flickr).

 

Food is an important part of life for Mecoptera, because many members of the Order use food as a gift to potential mating partners. The bigger the food gift (called a nuptial gift), the longer the male can mate with the female as she eats. Some males use dead prey as a nuptial gift, while others use a large, delicious ball of saliva. While spit in our food may be an act of vengeance by an annoyed waiter or irritating little brother, to Mecoptera there is nothing more appetizing.

 

By: Kallin Lang

Feature Photo by: Vlad Proklov, Flickr

 


Sources:
Avison, C. 2015. Scorpion Fly (Panorpa sp.) Female. [Internet] Available from: https://www.flickr.com/photos/colinavison/20016809903
 Contis. 2015. Order Mecoptera-Scorpionflies, Hangingflies, and Allies. Iowa State University: Department of Entomology. Available from: http://bugguide.net/node/view/56
 Discover Life. 2016. Mecoptera-Scorpionflies; Hangingflies [Internet]. Available from: http://www.discoverlife.org/mp/20q?search=Mecoptera
San Martin, G. 2010. Ladybird takeoff [Internet]. Available from: https://www.flickr.com/photos/sanmartin/4542045234.
 Hampshire, G. 2012. Scorpion Fly. Panorpa communis. Mecoptera. [Internet] Available from: https://www.flickr.com/photos/gails_pictures/7837166610
 Kaste, M. 2015. Open Cases: why one-thrid of murders in America go unsolved [Internet]. National public radio. Available from: http://www.npr.org/2015/03/30/395069137/open-cases-why-one-third-of-murders-in-america-go-unresolved
Lindgren, N.K., M.S. Sisson, A.D. Archambeault, B.C. Rahlwes, J.R. Willett, and S.R. Bucheli. 2015. Four Forensic Entomology Case Studies: Records and Behavioral Observations on Seldom Reported Cadaver Fauna With Notes on Relevant Previous Occurrences and Ecology. Journal of Medical Entomology 52(2):143-150. DOI: http://dx.doi.org/10.1093/jme/tju023
 Meyer, J.R. 2016. Mecoptera-Scorpionflies/Hangingflies. [Internet] General Entomology. Available from: https://www.cals.ncsu.edu/course/ent425/library/compendium/mecoptera.html
 Naskrecki, P. 2013. Scorpionflies. [Internet] Available from: https://thesmallermajority.com/2013/08/02/scorpionflies
 Pestaña, F. 2011. Mañanas entomológicas-Mosca esorpión hacienda limpieza en la casa de una araña-mecóptera-panorpa sp. [Internet] Available from: https://www.flickr.com/photos/ferranp/5875621989
 Proklov, V. 2014. DSC_4143. [Internet] Available from: https://www.flickr.com/photos/evergestis/14868053578
 Rogan, L. 2012. Hangingfly_4970. [Internet] Available from: https://www.flickr.com/photos/linda-rogan/8321348370
 Rutsch, P. 2015. Finding crime clues in what insects had for dinner [Internet]. National public radio. Available from: http://www.npr.org/sections/health-shots/2015/01/22/379091257/finding-crime-clues-in-what-insects-had-for-dinner
Walwyn. 2014. Scorpion fly Mecoptera [Internet]. Available from: https://www.flickr.com/photos/overton_cat/24233301812

The Truth About “Daddy Longlegs”

Daddy longlegs have the strongest venom in the world, but luckily their fangs cannot pierce human skin. This common myth, often first heard on elementary playgrounds, is still believed by many adults today. The name daddy longlegs actually refers to both cellar spiders and harvestmen, neither of which are harmful to humans. The harvestmen (Opiliones), our focus this week, don’t even produce venom at all!

 

Harvestman on a leaf.

From afar this may look like a picture of a spider. However, upon closer inspection, it can be seen that this individual is a harvestman. Photo by Marshal Hedin (Flickr).

 

This absence of venom is one of the defining features that distinguishes harvestmen from spiders, another group of visually similar arachnids. Harvestmen are often misidentified as spiders due to the fact that they both have eight legs and share the common name daddy longlegs with one member of the spider family. However, harvestmen do not have segmented bodies or produce silk like spiders do. Harvestmen are actually more closely related to scorpions and pseudoscorpions than spiders, despite their spider-y appearance.

 

While some people may think these multi-legged creatures are gross, they are actually quite clean. Harvestmen regularly groom themselves by performing an action called leg threading in which they slide each leg through their mouth. This allows the harvestmen to remove any parasites that might be attached to their legs. Harvestmen’s legs are essential for walking, eating, smelling, and breathing, and therefore their protection is highly important for survival. By threading their legs, harvestmen effectively safeguard their legs and minimize the threat of parasitism.

 

Daddy long leg on a hand.

A harvestman grooming its legs for parasites. Photo by Dallas Krentzel (Flickr).

 

In order to avoid getting eaten themselves, harvestmen have evolved additional behaviors. Well, a lack of behavior might be more accurate. Because most of their predators rely on movement to hunt, harvestmen benefit by being lazy! A typical day for this critter consists of crawling out of the crevice it calls home to moon-bathe on a nearby leaf, only to return back to its crevice when the sun comes up. Furthermore, if a predator disturbs an individual, the harvestman will curl up and remain motionless, playing dead, to avoid being seen. To repel predators further, harvestmen can excrete obnoxious-smelling chemicals when they sense danger to deter predators. As a last resort, harvestmen can even lose a leg in order to escape being eaten. Unfortunately, unlike other animals that use this escape mechanism, harvestmen’s legs do not grow back.

 

Some scientists believe that aggregating into large clumps further protects harvestmen from predation. Recent research shows that this strange behavior functions less for predation and more for water conservation. Harvestmen are very sensitive to dehydration due to their large amount of surface area. By crowding together, especially when the weather is dry, these bugs are able to conserve their water. The clumps can become enormous, with the largest recorded congregation containing 70,000 individual harvestmen. If 70,000 people were to aggregate, they could fill all of the seats in Gillette Stadium and still have a line of over 1,000 people out of the door.

 

Cluster of daddy long legs.

 Intriguing clustering behavior in which many harvestmen come together to preserve water. Photo by Josef Wells (Flickr).

 

While a huge mass of harvestmen may look like something out of a horror film, these bugs are nothing to be afraid of. As mentioned above, harvestmen are venomless and rely on their front pinchers to squeeze small pray to death. Another means for securing a meal is to scavenge for carcasses left behind by others. Rather than being dormant killing machines as they are described, harvestmen behave more like detritivores (eating decomposing plants, animals, and feces) than active hunters.

 

A harvestman hunting.

A harvestman about to snack on a small collembola, hidden in the top left corner of the photo. To kill collembola, harvestmen crush them with their muscular pinchers. Photo by Marshal Hedin (Flickr).

 

Harvestman eating Diptera (fly) prey.

A feeding harvestman. Since this bee is big, it is likely that it was already dead before the opportunistic harvestman found it. Photo by Marshal Hedin (Flickr).

 

Over the years, harvestmen have inspired an intimidating and persistent false reputation. Now, as harvestmen experts, it is up to you dispel the myths surrounding these harmless creatures and educate your peers on daddy longlegs.

 

 By: Kallin Lang

Feature photo by: John Flannery, Flickr

 

 


Sources
Bartlett, T. 2016. Order Opiliones-Harvestmen. Iowa State University: Department of Entomology. Available from: http://bugguide.net/node/view/2405
 Buddle, C. 2013. Ten fun facts about Daddy Longlegs. [Internet]. Arthropod Ecology. Available from: http://arthropodecology.com/2013/03/05/ten-fun-facts-about-daddy-longlegs
 Evans, A. 2008. Field Guide to Insects and Spiders of North America. Sterling Publishing Company, New York, New york. pp 404-405.
 Flannery, J. 2011. Harvestman. [Internet] Available from: https://www.flickr.com/photos/drphotomoto/6562222495
 Hedin, M. 2014. Opiliones, Eupnoi, F Sclerosomatidae, Leiobunum nigropalpi, male [Internet] Available from: https://www.flickr.com/photos/23660854@N07/14343985998
 Hedin, M. 2014. Opiliones, Dyspnoi, F Sabaconidae, Sabacon sp immature (probably S. occidentalis). [Internet] Available from: https://www.flickr.com/photos/23660854@N07/14808995458
 Hedin, M. 2009. Opiliones, Eupnoi, F Sclerosomatidae, Leiobunum vittatum group, male with prey. [Internet] Available from: https://www.flickr.com/photos/23660854@N07/3679665965
 Krentzel, D. 2012. Vonones ornate (Cosmetidae)-Time to groom. [Internet] Available from: https://www.flickr.com/photos/31867959@N04/6955043814
 McCarthy, E. 2014. 15 Fascinating facts about daddy longlegs [Internet]. Mental Floss. Available from: http://mentalfloss.com/article/59455/15-fascinating-facts-about-daddy-longlegs
 Viegas, J. 2014. Clump of Spiders? Viral video shows something else. [Internet]. Discovery News. Available from: http://news.discovery.com/animals/insects/clump-of-spiders-viral-video-shows-something-else-140102.htm
 Wells, J. 2014. 2014:07:06-13:47:12. [Internet] Available from: https://www.flickr.com/photos/josefwells/14662749639

A Living Fossil: Millipedes!

Many scientists quest to discover new species for their entire lifetimes, and still never get to name a novel animal. Mike Newman, an amateur fossil collector, accomplished this amazing feat accidentally. While on a walk through Stonehaven in northeast Scotland to scavenge for fossil fish, Newman stumbled upon an incomplete fossil of an ancient millipede. Though he did not know it at the time, this fossil was actually the oldest known living terrestrial animal, beating the previous record by over 20 million years. This species, now called Pneumodesmus newmani (after Newman) lived approximately 400 million years ago, back when plants first left the water to colonize land.

 

Fossil millipede, Pneumodesmus newmani.

This unassuming rock actually contains the oldest land animal ever known, the Pneumodesmus newmani. Photo by EOL Deep Time Group (Flickr).

 

Even though millipedes have been around for a long time, there are still many misconceptions about them. For example, the name ‘millipede’ comes from the Latin roots milli meaning thousand and ped meaning foot. This has earned the animal the nickname ‘thousand leggers.’ Despite this name, not one identified individual has even approached 1000 legs. In fact, the leggiest millipede (and animal) in the world has only 750 legs! Most adult millipedes have less than 100 legs and can even have as few as 22 legs. Born with only three pairs of legs, millipedes add new legs during molts (growth of the body and shedding of the now too-small outer shell) that occur in underground chambers. These chambers protect the invertebrate from predators during their vulnerable molting period. After many molts, adult millipedes finish with anywhere from 22 to 750 legs (11 to 375 pairs of legs).

 

Millipede on a mossy log.

This living fossil can be found in moist locations in forests, such as leaf litter, on mossy logs, or on protected tree trunks. Photo by David Dennis (Flickr).

 

This leg mishap leads to another common problem: untrained eyes mistaking millipedes for centipedes. Centipedes, or ‘hundred leggers,’ also suffer from miscounting – they often do not have 100 legs. In fact they can have anywhere from 30 to 354 legs (15 to 177 pairs of legs). Because each Order has a variable number of legs, which aren’t reflected by their names, identification can be tricky. However, when looking at other characteristics, the difference between centipedes and millipedes becomes readily apparent.

 

Millipede infographic.

Infographic highlighting key characteristics of millipedes. Photo by Subash BGK (Flickr), cropped by Kit Straley. Infographic by Kit Straley.

 

Centipede infographic.

Infographic highlighting key characteristics of centipedes. Photo by Alan Davey (Flickr), cropped by Kit Straley. Infographic by Kit Straley.

 

Millipedes and centipedes can be differentiated by their behaviors, such as their defenses. Centipedes are predators – when they are faced with danger, they quickly run away. If fleeing isn’t an option, they can use their predatory venom to defend themselves. Millipedes, on the other hand, are quite slow and venom-less. Instead, they have developed numerous ways to keep themselves safe without moving at all. First, they can use their hard exoskeleton (outer shell made of tough material). When millipedes sense danger, they curl up into a ball protecting their soft underbelly.

 

Alternative images of the same millipede, 1 in which it is curled and 1 in which it is not.

The same individual, in its defensive curled up position vs. its normal posture. Photo by John McCullough (Flickr).

 

Bristles are another unique defense mechanism used by one species of millipede. The species, found in Europe and North America, detaches its bristles on the mouthparts and antennae of an attacking ant. Naturally, the ant tries to clean the bristles off. This action actually hurts the ant more because the strands have barbs that hook in. This method works on ants and other predators like centipedes, spiders, pseudoscorpions, and beetles.

 

A bristle-covered millipede.

This species of millipede, Polyxenus lagurus, uses its bristles as a defense mechanism. Photo by Andy Murray (Flickr).

 

Millipedes can also release noxious chemicals to ward off predators. These chemicals can function as irritants, repellents, or antifeedants (chemicals that harm predators once consumed). Certain millipedes have even evolved a coordinated release of two compounds that interact to form cyanide gas! This gas kills attacking arthropods, but can also be produced in high enough concentrations to kill small vertebrates.

 

Millipedes, like many other prey animals, use bright red or yellow patterns to warn predators that they are toxic to eat. This is called aposematic coloring. In order for the eat-me-and-die! signal to work, predators have to be able to see it. Members of one group of millipedes, the Motyxia, are nocturnal. Their predators cannot detect color differences during the night, so Motyxia have instead evolved to glow in the dark! This bioluminescence (production of visible light by a living thing) serves as an alternative warning to predators.

 

Glow in the dark millipede.

A member of the Motyxia group A) during the daylight, and B) without light. (Figure 1 from ‘Bioluminescent aposematism in millipedes’ by Marek et al. 2011).

 

Despite the numerous defense mechanisms that millipedes possess, these creatures are often a tasty meal for other animals and a vital link in the food web. Luckily, millipedes lay between 20 and 300 eggs at a time and are able to maintain high numbers. Their ability to produce so many young, combined with anti-predator behaviors, might explain how they’ve managed to stick around for so long.

 

By: Kallin Lang

Feature photo by: Tanner Nygren, BLM New Mexico, Flickr.


 

Sources
Andries, K. 2012. World’s Leggiest Animal Found Near Silicon Valley. [Internet]. National Geographic. Available from: http://news.nationalgeographic.com/news/2012/11/121114-leggiest-animal-millipede-illacme-plenipes-silicon-valley-science
 Catchpole, H. 2004. Millipedes were first to shift to land. [Internet]. ABC Science. Available from: http://www.abc.net.au/science/articles/2004/01/27/1031780.htm
 Davey, A. 2009. Centipede. [Internet] Available from: https://www.flickr.com/photos/adavey/5051703601
 Dennis, D. 2007. Millipede. [Internet] Available from: https://www.flickr.com/photos/davidden/2210327776
 Eisner, T., M. Eisner, and M. Deyrup. 1996. Millipede defense: Use of detachable bristles to entangle ants. Proceedings of the National Academy of Sciences of the United States of America 93:10848-10851.
 EOL Deep Time Group. 2014. Pneumodesmus_newmani. [Internet] Available from: https://www.flickr.com/photos/124773749@N07/14859045508
 Evans, A. 2008. National Wildlife Federation Field Guide to Insects and Spiders and Related Species of North America. Sterling Publishing Company, New York, New york. pp 417-424.
 Gray, E. 2015. Millipedes and Centipedes. [Internet] University of Georgia extension. Available from: http://extension.uga.edu/publications/detail.cfm?number=B1088
 Nygren, T. 2013. 5th place: Millipede. [Internet] Available from: https://www.flickr.com/photos/blmnewmexico/14111552281
 Marek, P., D. Papaj, J. Yeager, S. Molina, and W. Moore. 2011. Bioluminescent aposematism in millipedes. Current Biology 21(18):R680-R681.
 McCullough, J. 2006. Millipede, protecting himself. [Internet] Available from: https://www.flickr.com/photos/cup_prof/243091059
 McCullough, J. 2006. Millipede, on the move [Internet] Available from: https://www.flickr.com/photos/cup_prof/243090990
 Murray, A. 2012. Bristly millipede- Polyxenus lagurus. [Internet] Available from: https://www.flickr.com/photos/andybadger/7129795635
 Okrin. Centipedes vs. Millipedes [Internet]. Available from: http://www.orkin.com/other/centipedes/what-is-the-difference-between-centipedes-millipedes
 Okrin. How many legs does a centipede have? [Internet]. Available from: http://www.orkin.com/other/centipedes/how-many-legs-does-a-centipede-have
 Shear, W. 2015. The Chemical defenses of millipedes (diplopoda): Biochemistry, physicology, and ecology. Biochemical Systematics and Ecology 61:78-117.
 Subash, B.G.K. 2014. Millipede, black millipede. [Internet] Available from: https://www.flickr.com/photos/subashbgk/14770736676

Back to Spring with Springtails

From learning to dougie to summoning rain, different types of dancing evoke a variety of emotions and are used for many distinctive purposes. For Collembola (commonly referred to as springtails), our featured bugs this week — a good dance might just find you a girlfriend.

 

andymurray3

Two members of the Order Collembola “dancing.” The male is smaller and orange, while the larger red individual is female. The photographer Andy Murray (Flickr) said that this particular dance was successful!

 

The “Cha-Cha-Cha”dance of one species of springtail (not to be confused with our “Cha-Cha Slide”) is a dance that involves a series of head-butts (seen above) with a grand finale of two twirls. While it may seem aggressive to the human eye, this dance, when completed satisfactorily, woos a female Bourletiella hortensis into accepting a male’s sperm packet, or spermatophore. However, if she is less than impressed, the female declines his offer and eats the spermatophore instead! These sperm sacs must be nutritious, because males of the Orchesella cincta species are often seen eating the sperm sacs of other males. Scientists propose that by eating competing males’ sperm, Orchesella cinta increase the chances of their sperm packets being chosen by neighboring females instead.

 

gillessanmartin copy.jpg

This male springtail has just deposited his sperm packet (spermatophore). Photo by Gilles San Martin (Flickr). Edited by Kallin Lang, cropping and adding a label.

 

As an alternative to dancing, some male springtails use the “love garden” technique, planting a series of spermatophores in an area and then coaxing a female springtail to walk through and pick up sperm along the way. Other males are much more strategic with their placement of sperm. Some use the “ring of fire” method, which involves building a fence around the female, practically forcing her to walk over a sperm packet if she wants to leave. However, some males in this Order are much more careless, haphazardly depositing their spermatophores and hoping that a female will find it. This reproductive method is known as “drop and pray.” Lastly, others use the “tug of war” technique. After laying a spermatophore, a male grabs onto a female with his antennae and forcefully brings her over to it. In species that don’t directly transfer sperm, males have to get a little creative.

 

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The top photo is from our lab, and shows a species of Collembola that we have affectionately nicknamed “Punk-rock Collembola.” Photo by Kit Straley. The bottom photo, by photographer Andy Murray (Flickr) shows a similar species in much finer detail. Check out those spikes!

 

In addition to their different mating rituals, springtails also exhibit other interesting behaviors. Some members of the Order can jump anywhere from 15 to 20 times their own body length when threatened, using specialized legs that are normally kept tucked against their bodies. This is equivalent to a 5’5” tall person jumping over 8 stories high. This amazing feat earned them their nickname “springtails.” To land safely after such a leap, it was once thought that Collembola had a specialized organ which allowed them stick to whatever they landed on. In fact, this is how the Order got its scientific name. The greek roots kolla, meaning glue, and embolon, meaning peg were combined into Collembola. Unfortunately, scientists made a mistake. This “glue-peg,” which is located just before the third set of legs, is actually used in transporting water in and out of the individual, not to stick to surfaces. Despite this, the name stuck and over 200 years later the bug is still known as Collembola.

 

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The picture above shows two of the defining characteristics of the Order: the glue-peg and the springtail. Collembola can be elongated like above or more spherical like below, but always have short antennae and eye patches made up of multiple eyes. Photo by the NY State IPM Program at Cornell University (Flickr). Edited by Kallin Lang to include labels.

 

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While from far away it may seem that springtails only have two eyes, when you zoom in like the photographer Andy Murray did here, you can clearly see that the “eye” is actually a cluster of multiple eyes (Flickr).

 

Considering how Collembola are so cool, why aren’t people talking about them? They are so tiny! Even at their largest size of 6mm, you could still fit three end to end on a penny and have room to spare. These bitty bugs can be found anywhere from within soil, leaf litter, and decaying wood to the surfaces of water or snow. While they much prefer to be the one chowing down on some decaying leaves, mold, or mildew, these tiny bugs often find themselves on someone else’s dinner plate. Other insects and arthropods such as spiders, mites, flies, and pseudoscorpions perceive them as tasty snacks rather than friendly neighbors. You would think with up to 8 single eyes on each side of their head they would keep a better lookout! Regardless, if they can see you coming with their multitude of eyes, you should definitely keep your two on the ground. You never know when you might run into a leaping Collembola.

 

By: Kallin Lang

 Feature photo by Andy Murray, Flickr.


 

Sources:
Carr, J. 2009. Class: Collembola-Springtails and allies. Iowa State University Department of Entomology, Aimes, IA. Available from: http://bugguide.net/node/view/258362
Hopkin, S. 1997. Biology of Springtails (Insecta: Collembola). Oxford University Press, Great Britain. pp 139-140.
Murray, A. 2012. Deuterosminthurus pallipes courtship ritual. [Internet] Available from: https://www.flickr.com/photos/andybadger/718320509
Murray. A. 2013. Calvatomina rufescens. [Internet] Available from: https://www.flickr.com/photos/andybadger/9573043357
Murray. A. 2013. Orchesella villosa. [Internet] Available from: https://www.flickr.com/photos/andybadger/9631275944/
NY State IPM Program at Cornell University. 2012. Springtail. [Internet] Available from: https://www.flickr.com/photos/99758165@N06/
San Martin, G. 2008. Sminthurus viridis (det F. janssens). [Internet] Available from: https://www.flickr.com/photos/sanmartin/2419124883/in/photolist-nprV8W-4FLDxH-bczv18
Shockley, F. 2011. It takes two to tango…or does it? The curious courtship of Collembola. Decoded Science [Internet]. Decoded Science. Available from: http://www.decodedscience.org/it-takes-two-to-tango-or-does-it-the-curious-courtship-of-collembola-springtails/3713
Van Duinen, J.J. 2016. Class Collembola Lubbock, 1870: Springtails general. [Internet] Available from: http://www.janvanduinen.nl/collembolaengels.html

Pseudoscorpions: Pinchy Hitchhikers?

 

Tiny Size

Pseudoscorpion on the tip of a finger. This tiny critter spins silk, incapacitates small insects with venom from its claws, and may even live in your house. Photo by Kyron Basu, BugGuide.net.

 

I came to school to study birds, and as luck would have it many birds eat bugs, so now I spend most of my time with bugs. I thought that this shift in subject would be a total bummer, completely boring, and let’s be honest – gross. Bugs can be pretty terrifying, especially if you don’t understand their behavior and why they have such odd strategies for life.

One day, I was dumping out a jar full of preserved bugs from some forest leaf litter I’d collected from one of my field sites. I put the insects under a microscope and was shocked to see what looked like an adorable, teeny tiny scorpion. But wait – It couldn’t possibly be a scorpion! I collect my samples in Massachusetts, not a desert state in the southwest. Also, this scorpion seemed to be missing its tail. As I kept encountering more and more of these tail-less individuals, I realized that this must be something entirely different.

 

Magnified Pseudoscorpions

Three pseudoscorpions under a microscope. They are smaller than a grain of white rice! Photo by Kit Straley.

 

They’re called pseudoscorpions, belonging to the Pseudoscorpiones group of arachnids related to true scorpions and spiders. There are over 3,500 species of them worldwide, a whopping number when you consider that there are less than 300 species of mammals belonging to the Carnivora group. North America in particular has approximately 420 species.

 

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Figure from Buddle (2010) illustrating the diversity of pseudoscorpions in size, shape, and color.

 

These creatures are incredibly diverse and exist worldwide. Despite their high levels of diversity, they are rarely seen because they live under bark or stones, in leaf litter or mosses, and between the boards of buildings. One particular species even lives in houses, hunting the small insects that would otherwise be house pests. Should we be scared? After all, they do have tiny pinching claws that produce venom.

 

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Close up of a “thoughtful” pseudoscorpion. Photo by Dennis Spamlin, Flickr.

 

Pseudoscorpions are not harmful to humans, and are in fact helpful! They do not damage property, eat tiny pests like mites, and their venom is not dangerous to us in such small amounts.

Now that we’ve gotten that concern out of the way, let’s focus on what makes them so incredibly cool: their behavior. Pseudoscorpions are tiny. Individuals that are the size of rice are actually the LARGE ones. It must be tough for creatures so small to move long distances on their own. So how do they get around to far away places? Do they contently reside in the same patch of moss? No!

They hitch a ride. Pseudoscorpions have been documented hitchhiking on all kinds of flies and beetles. In one particular study of their hitchhiking, scientists found that males even BATTLE IT OUT on the backs of beetles to establish mating territories should a female hop on.

 

Hitchhiking

Pseudoscorpion hitching a ride on a fly. Hold on tight! Photo by Tom Murray, BugGuide.net

 

For mating, males deposit sperm packets on the ground for the females to pick up. Sometimes she finds it on her own, sometimes he helps her out by leaving a trail of silk to guide her, and sometimes he just straight up drags her over the sperm pile to make sure she doesn’t miss it!

The female can use her silk, which unlike spiders does not come out of her rear end but rather her claws (true spiderman-style), to build a hidden retreat while she tends to the eggs. Males can spin silk, not only to help females find sperm but also to build secluded spaces in which they overwinter.

What an awesome and hilarious creature. So far I’ve only gotten to see them in my preserved samples, under a microscope. One day I hope to see a live male pseudoscorpion in the woods, riding his majestic beetle steed, hoping to impress a lady.

For more information on pseudoscorpions, check out this blog post by Christoper Buddle or any of the sources at the bottom.

By: Kit Straley

Feature photo by Andy Murray, Flickr.


Sources:
Bartlett, T., R. McLeod, C. Wirth, C. Entz, G. Montgomery, C. Eiseman, J.C. Trager, and V. Belov. 2014. Order Pseudoscorpiones – Pseudoscorpions [Internet]. Iowa State University Department of Entomology, Ames, IA; [cited 2016 Feb 13]. Available from: http://bugguide.net/node/view/2892.
Borror, D.J. and R.E. White. 1970. A field guide to the insects of America north of Mexico. Houghton Mifflin Co., Boston, MA. pp 54-55.
Buddle, C.M. 2010. Photographic key to the Pseudoscorpions of Canada and the adjacent USA. Canadian Journal of Arthropod Identification 10:1-77.
Eaton, E.R. and K. Kaufman. 2007. Kaufman Field Guide to Insects of North America. Hillstar Editions L.C., New York, NY. pp 24.
Evans, A.V. 2007. National Wildlife Federation Field Guide to Insects and Spiders of North America. Sterling Publishing Co., New York, NY. pp 409.
Harvey, M.S. 2011. Pseudoscorpions of the World, version 2.0. Western Australian Museum, Perth; [cited 2016 Feb 13]. Available from: http://www.museum.wa.gov.au/catalogues/pseudoscorpions.
Harvey, M.S. 2013. Order Pseudoscorpiones. In: Zhang, Z-Q. Animal biodiversity: An outline of higher-level classification. Zootaxa 3703(1): 34-35.
Milne, L. and M. Milne. 1980. National Audubon Society: Field Guide to North American Insects and Spiders. Chanticleer Press, Inc., New York, NY. pp 917.
Triplehorn, C.A. and N.F. Johnson. 2005. Borror and DeLong’s introduction to the study of insects, 7th ed. Thomson Brooks/Cole, Belmont, CA. pp 135.
Zeh, D.W. and J.A. Zeh. 1992. On the Function of Harlequin Beetle-Riding in the Pseudoscorpion, Cordylochernes Scorpioides (Pseudoscorpionida: Chernetidae). The Journal of Arachnology 20:47-51.