Week Seven: Scabies Mite

Common Name: Scabies mite

Scientific Name: Sarcoptes scabiei var. Hominis

Not-So-Fun Fact : Scabies, the condition caused by this organism, is an excruciatingly uncomfortable disease characterized by irritation, rash, and itching. Napoleon Bonaparte, a victim of the disease, was often so overcome with the itching that his soldiers would think that he had been wounded terribly in battle. In fact, he had been scratching at his terrible rash. Writing and researching this entry by itself is making me feel awfully itchy.

Domain : Eukaryota

Kingdom : Animalia

Phylum : Arthropoda

Class : Arachnida

Family : Sarcoptidae

Genus : Sarcoptes

Species : S. scabiei

Subspecies: variant hominis

Description: The organism responsible for scabies is a very small, fat, short-legged mite. A scabies mite grows up to 0.45 millimeters, with its body vastly larger in proportion to its minuscule head and stubby legs.

Environment: The scabies mite spends its entire life either underneath or crawling along the surface of its host’s skin.

Reproduction & Development: The scabies mite reproduces sexually and lives for up to two months. After mating just once, the female moves into the skin of its human host and begins to lay eggs subcutaneously. Once her larvae hatch, they go through a series of stages as a nymph in the upper layers of the host’s skin. Once they reach their adult forms, the mites continue the mating cycle, with pregnant females migrating along the outer surface of the host in order to find a new dwelling.

Nutrition: Scabies mites are parasites which feed on the blood of their host. This particular variant feeds on the blood of humans. The rash and irritation associated with scabies actually results from the presence of the mites themselves, along with their excretions.

 

 

 

Week Six: Blue-Ringed Octopus

Common Name: Blue-Ringed Octopus

Scientific Name: Hapalochlaena lunulata

Not-So-Fun Fact: The blue-ringed octopus carries an extremely venomous bite caused by colonies of bacteria in its saliva which produce a neurotoxin called tetrodotoxin. Tetrodotoxin prevents sodium from being transported across membranes in the brain and can kill those exposed in less than an hour.

Domain: Eukaryota

Kingdom: Animalia

Phylum: Mollusca

Class: Cephalopoda

Order: Octopoda

Family: Octopodidae

Genus: Hapalochlaena

Species: H. lunulata

Description: The blue-ringed octopus is a small octopus with bright yellow skin covered in blue circular markings. Its vivid coloration warns potential attackers of its extremely venomous bite. The greater blue-ring’s mantle can grow up to 55 millimeters, but a more average length for adult individuals is 25 to 40 millimeters. The skin is covered in pebbly papillae. When agitated, the yellow hue of the octopus’s skin deepens to golden brown; the blue rings thicken, brighten, and may pulsate; and the papillae become smooth.

Environment: The greater blue-ringed octopus is native to the Indian and Pacific oceans, and inhabits a range stretching from Sri Lanka to northern Australia, Papua New Guinea, the Solomon Islands, the Philippines, and Indonesia. Visitors to Australian beaches are put at risk by the presence, and a few fatalities are reported each year as a result of bites or extended contact with the octopi.

Reproduction & Development: This organism reproduces sexually, and the mating process is a very long and close process. The females lay eggs whose gestations last about two months, the total time depending on temperature. Their offspring become sexually mature after about four months and usually live for about eighteen months. During gestation, the eggs are held by the female’s long tentacles and kept close to her body.

Nutrition: The blue-ringed octopus is a very small predator, and normally feeds on small crabs, hermit crabs, and shrimp dwelling near the shore. They eat such crustaceans by attacking them, wrapping their bodies around them, and puncturing their carapaces with their sharp, venomous beaks.

 

Week Five: Datura

Common Name: Datura, Jamestown Weed, Angel's Trumpet, Devil's Apple, Thorn Apple

Scientific Name: Datura stramonium


Not-So-Fun Fact: Datura is highly poisonous. During an uprising in the late seventeenth century in the then-colony of Virginia, colonial rebels contaminated the authoritarian soldiers’ food with the hallucinatory plant to incapacitate them and render them clinically insane for more than a week. While the rebellion itself failed, this ploy succeeded, with horrifying results.

Domain: Eukaryota

Kingdom: Plantae

Phylum: Magnoliophyta

Class: Magnoliopsida

Order: Solanales

Family: Solanaceae

Genus: Datura

Species: D. stramonium

Description: Datura is a small, pretty plant with a woody stem and broad, weedy leaves. The plant can grow to two to three feet in height and is studded with flowers and seedpods described in fuller detail under Reproduction & Development. All parts of datura, especially the seeds are poisonous, and contain tropane alkaloids that if ingested cause fever, hallucinations, seizures, madness, brain damage, coma, and death.

Environment: Datura is native to Central America, but is found in most parts of the southern United States. The plant prefers a warm temperate to tropical climate. British settlers in the Americas first encountered datura when they attempted to eat the weeds found on Jamestown Island, and later the horrific poison was used against the Loyalist authorities in the rebellion of the late 1600s.

Reproduction & Development: Datura is a flowering plant which produces long, trumpet-shaped blossoms in white or violet. These later give way to small, egg-shaped green seedpods whose protective casings give it the nickname “thorn apple”. The seedpods split open to release the many highly toxic seeds. The unfortunate 1607 settlers found the plant rather plentiful on Jamestown.

Nutrition: Datura relies on sunlight, water, and soil nutrients to survive, as is usual among plants. It can thrive in most warm conditions, from the dry southwest to the swampy Virginia eastern habitats so beloved by mosquitoes.

 

Week Four: Bull Shark

Common Name: Bull Shark

Scientific Name: Carcharhinus leucas


Not-So-Fun Fact: Bull sharks are placed among the most dangerous sharks in the world, next to tiger sharks and great whites, because of their high aggression. It has been postulated that this is because of increased levels of testosterone in the shark’s body in comparison to other fish. An important fact to be considered, of course, is that shark attacks, let alone fatalities, are very rare: it has been estimated that it is more likely for a person to be killed by a collapsing vending machine than for that person to be the victim of a fatal shark attack.

Domain: Eukaryota

Kingdom: Animalia

Phylum: Chordata

Class: Chondrichthyes

Order: Carcharhiniformes

Family: Carcharhinidae

Genus: Carcharhinus

Species: C. leucas

Description: Bull sharks are heavyset, extremely powerful sharks. They can measure up from seven feet to more than eleven feet from their muscular tails to their tapering, blunted snouts. Their backs are dark gray and their underbellies are white, in order to camouflage them from other ocean dwellers looking up into the light or down into the depths. Their pectoral fins are remarkably long, and the tips may be a darker color than their backs. A bull shark features an impressively large collection of  sharp teeth, which are lost and replaced at a very high rate.

Environment: Bull sharks enjoy warm, shallow waters, and can be found in any ocean that supplies this habitat. There have been many cases of the sharks swimming upriver and into freshwater habitats, which makes them a greater threat to humans than they might otherwise be.

Reproduction & Development: Unlike most fish, bull sharks give birth to live young, which hatch from eggs inside the female’s abdomen. One to three “pups” may be born at any one time. Gestation is typically ten to eleven months. Bull shark young keep to coastal areas and only venture more widely as adults. A bull shark usually lives up to sixteen years in the wild.

Nutrition: Bull sharks are carnivores at the top of the oceanic food chain, and eat mainly large fish, smaller sharks, and rays, though their selection of prey may extend to shellfish and crustaceans. Bull sharks may even be cannibalistic in some cases.