Sign of Spring

White Trout Lilies, Erythronium albidum

It is my favorite time of year when the trout lilies are starting to bloom. They are a rare wildflower due to their habitat preference and long propagation time; however, they are earlier bloomers and often considered a herald of spring. Although I have written an in-depth post about them already, today seemed a good day to revisit the topic, with some more photos of their blooming, and a reminder about the post linked above where you can read more information.

Leaf litter may hide them as they bloom, but they are there if you look!

Next week and perhaps the week after I plan to focus my posts on birds. To make it interesting, I hope to do an identification game similar to last year with the bark on Google+, except instead of pictures, I'll post the bird call and allow for guessing. The songs will be posted on Monday and Wednesday.

Fall Webworm: Moth

Fall Webworm Moth, Hyphantria cunea

The fall webworm is native to North America and can be found from southern Canada to northern Mexico. It has become an invasive pest throughout Europe and Asia, and is often considered a pest in its native range for its preference to feed on ornamental plants and agricultural crops. Although the large webs created by larvae in any of its numerous host trees looks damaging, even severe infestations have little impact on trees as it is during the end of the growing season.

Orange hairs on the prothorax and foreleg can help in identification.

The adult form of the fall webworm has geographical distinctions. In the north, the moth is usually all white while in the south it is more heavily marked with dark spots. The adult form can be spotted year round in many southern locations, but fall webworm moths are generally limited to the summer months. The larval form is often more readily observed than the nocturnal adult form.

Red-eared Slider

(Older) Red-eared Slider, Trachemys scripta elegans

The most common aquatic turtle in Texas is the red-eared slider. While more obvious in younger turtles, red-eared sliders are overall green with a head marked by yellow stripes and a characteristic red stripe behind the eye. Like other Testudines, they exhibit sexual dimorphism in terms of size with males averaging 158 mm (6.2 in) and females averaging 246 mm (9.7 in). Their typical longevity is 9 to 13 years, but they have been recorded to living up to 37 years. Red-eared sliders prefer permanent, slow-moving water such as ponds and consume aquatic plants, small fish, and decaying matter. While native to the Mississippi Valley from Illinois to the Gulf of Mexico, red-eared sliders have been introduced throughout the rest of the United States as well as other countries. As they were once a popular dime store turtle, it is believed most introductions are the result of accidental and intentional releases of previous pets.

Chinese Privet

Chinese Privet, Ligustrum villosum

Chinese privet is an evergreen shrub with spreading branches. The leaves are opposite, the flowers white and fragrant, and the berries bluish black and persistent throughout winter. While the seeds are dispersed by birds, Chinese privet also reproduces by root suckers. Unfortunately, this ornamental shrub that was introduced in 1852 is very invasive in much of the southern United States. As with other invasive species, Chinese privet can tolerate many conditions and poses the threat of forming dense thickets and creating monocultures. In addition to making conditions unsuitable for native seedlings, compounds in the leaves prevent many native herbivorous species from feeding on the plant. As Chinese privet is considered one of the most invasive plants for many different states, it is highly discouraged for planting. Current control of Chinese privet includes physical removal of planets, especially before seeding, and a few different herbicidal methods including foliar spraying, cut stump applications, and basal bark applications.

Bluegill

Bluegill, Lepomis macrochirus

Also known as bream, brim, and sunfish, bluegills are freshwater fish of the genus Lepomis, a name derived from Greek which roughly means scaled gill cover. While other common names include perch and sunperch, they are not related to perch which belong to the genus Perca. Bluegills can be found in streams, rivers, lakes, and ponds, and prefer to hide in debris found within bodies of water. While their native range is mainly along the Great Lakes and Mississippi River, they can be found in most states where they have been unintentionally and intentionally introduced, especially as fodder for the sporting fish largemouth bass. Bluegills can reach up to 30 cm (12 in) in length and though they will feed on smaller fish, they will also feed on water fleas, frogs, and various insects.

Largemouth Bass

Largemouth Bass, Micropterus salmoides

The largemouth bass, green with a horizontal stripe of dark blotches, also goes by the names of black bass, green trout, and lineside bass. It is one of the most widely distributed fishes in the world due to their popularity as sports fish. These fish reach lengths of 40 cm (16 in) by their third year, but may reach longer lengths. Their large, sloping mouths extend past their eyes which is essential for being a top predator in the water. While perches, walleyes, pikes, and waterfowl feed on smaller bass, once large enough, a largemouth bass will feed on other fish, including perches, as well as frogs, crayfish, and insects.

Water fleas: Daphnia

Water flea, Daphnia spp. likely feeding while anchored to glass.

Water fleas are crustaceans of the order Cladocera. In general, these creatures range in sizes of less than 0.5 mm to more than 6 mm with males being smaller. Within Cladocera are the planktonic crustaceans of the genus Daphnia which are characterized by their flattened leaf-like legs. Their bodies are enclosed by an uncalcified shell with either five or six limbs on the trunk. In the water, they swim in a jumping-like behavior that earned the nickname of water fleas. There are more than 100 known species within Daphnia that have been studied for more than 250 years.

Transverse perspective of Daphnia spp. swimming.

Daphnia are mostly freshwater microcrustaceans that can be found in most types of freshwater including permanent and temporary ponds, lakes, and slow moving streams. While mostly pelagic, some are found clinging to plants or browse in the bottom of shallow ponds. They are filter feeder, their prey the small, suspended particles in the water, mostly consuming planktonic algae. Their leaf-like legs are used to produce a water current to collect the particles. They mature fast and serve as an important source of food for fish and other aquatic organisms.

Transparency of Daphnia has been useful in various research projects.

There are numerous reasons why Daphnia has been subject to intense biological investigations for more than a century. Their transparency allows for the conduction of bioassays using endpoints other than death such as heart rate or changes in appetite. The wide distribution of Daphnia, from freshwater lakes to saline ponds, means the manifestation of extensive diversity allowing for the study of gene function and genome by environmental interactions. They are often used as a model for ecotoxicological studies. In addition, they are a valuable outgroup for comparative genomic studies, particular due to their close relationship to insects which have provided for study of genome function and evolution. The fast maturity of Daphnia, as well as asexual reproduction that can be induced environmentally to be sexual, adds to their appeal for study. We have learned much from Daphnia, from genetics and epigenetics to immunology and toxicology, all that can be applied to humans, but there is plenty more left to learn.


Edit: Another version of this post with more focus on Daphnia in research was written this past Sunday and can be found here along with three photographs not on the blog.

Ballooning Spiders

Video-turned-gif of ballooning spiders in action.

Aerial migration is not limited to birds. It is also not limited to insects with wings. On any given day, there may be millions, or even billions of insects passing over head, and this vast collection of invertebrates often do include spiders. While possibly contrary to the belief of some, and given the right weather conditions, spiders can fly in a phenomenon known as dynamic kiting, or spider ballooning, and it is a phenomenon that Darwin recorded during his voyage aboard the HMS Beagle.

Two spiders attempting to launch on top a tall post.

Ballooning spiders disperse in enormous numbers, most often seasonally. Although they lack wings, they have their *silken threads that can passively carry them* on the wind. When it is warm enough for a thermal updraft and the wind isn’t too strong, some species of spiders, hatchlings and adults, climb to the top of a tall object. From there they face the wind, stand with abdomen raised, and release a silken strand or more known as gossamer. Once airborne, the spider rides the wind for possibly hundreds of miles and many, many days.

Ballooning isn't limited to a single spider species.

While thermal air currents play a role, it is possible that the electrostatic force is equally or more important in giving spiders a lift. It is currently believed that the force comes from a combination of the electrostatic field of Earth’s atmosphere, friction between the silk and dry air, and the rest from the spinning process and launch surface. Not only may this explain how heavier spiders launch themselves into the air, but it also explains how the silk threads fan out – negative charges repel.

More than one spider sometimes try to use the same launching grounds.

Whether to travel hundreds of miles or only a few feet, ballooning spiders is a notable phenomenon, especially when it is a mass of spiders taking advantage of a single good day of weather. A large enough event often times captures the attention of media, and even a reported sighting of a UFO was attributed to this phenomenon. In the end, it’s only some spiders looking for a new place to live.


This post is another rehash of an earlier Science Sunday post, but with a few different pictures. The original post can be found here along with an animation of ballooning spider launching mechanism (though it is slightly out-of-date). Do note that Thursday's post will be a bit different in that, for once, it'll be my Science Sunday post, but posted before that Sunday. Stay tune!