LSM1303 Animal Behaviour

After watching a documentary on parasites on Animal Planet, I learnt about Tumbu Flies from Central Africa.

To summarise, scientist Karl Loren spent 3 years in Africa, and he realised that he was getting pimples on his skin. After a while, these pimples grew itchier and itchier. At some point these pimples grow bigger, redder, and turned to sores. Some time later, these lumps on his skin began to move. By then it was already too painful, and he stopped work and tried to dig the sores open.

“The tumbu fly is found in many parts of East and Central Africa. It lays eggs on clothing – especially clothes that bear traces of urine or sweat. Clothes hanging outdoors on the washing line and clothes laid out on the ground to dry are the usual target.”

“The eggs hatch on contact with human skin. The larvae burrow into the skin and produce a characteristic boil, which contains not pus, but a developing maggot. The boils are usually multiple and are most often over the back, arms, scrotum, and around the waist.”

“The breathing apparatus of the maggots can usually be identified at the surface of the boil as a pair of black dots. A maggot can be removed by placing water or oil over its breathing apparatus and gently squeezing it; the maggot will pop out. This is a rather unpleasant spectacle to witness.”

This condition is known as Myiasis, which is the infestation of live animals with larvae, which at least for a period, feed on the host’s dead or living tissue. Fortunately for Loren, he got the help of a native African doctor, who covered his sores with coconut oil until the maggots came to the surface of the skin and they dug out the maggots one by one. I can’t imagine being eaten alive like that.

References:

Animal Planet: TV With Teeth – Nature’s Vampires

Karl Loren (2003). The Bite? of the African Insect? That lays egges that burrow. http://www.karlloren.com/biopsy/p47.htm

James AS, et al; Cutaneous myiasis due to Tumbu fly. (Arch Emerg Med, 1992 Mar, Abstract available) [MEDLINE]

The nile crocodile, Crocodylus niloticus, is known to be one of the most ferocious carnivores. It eats almost anything that comes within its proximity and can eat up to half of its body weight! We do sometimes hear of people and of course animals getting killed by the nile crocodiles. The nile crocodile’s indiscriminate eating has probably given it its reputation of being a ferocious eater.

Nile crocodile lunging at its prey

(http://www.flickr.com/photos/lipkee/2881752455/)

However, no matter how ferocious the nile crocodile might seem to be, it is surprisingly a caring parent! Each time, a female would lay 25-75 eggs and they would guard it closely for up to three months while the eggs go through incubation. When the eggs hatch, they would also help out so as to ensure that the babies emerge smoothly.

One interesting thing which happens just before the hatching is that the young would actually call out to its parent while it is still inside the egg! This sound is actually made to by the young to protect itself as when the sound is made, the parent crocodile would know that the young is hatching and would hence protect its young from any potential predators in the area. Such an action enables the young to receive adult care and protection immediately once it is born.

Even though the nile crocodile is known to be ferocious, it is still a loving parent which protects its young! I guess this applies to many animals as well. Thus, never always think that a ferocious animal is never a good parent! Does the nile crocodile look a little lovelier now?

lovely parent?

(http://www.flickr.com/photos/arnolouise/494439876/)

references:

http://www.sciencedaily.com/releases/2008/06/080623125006.htm

http://www.bbc.co.uk/nature/wildfacts/factfiles/3118.shtml

http://animals.nationalgeographic.com/animals/reptiles/nile-crocodile.html

Tsetse fly

Image courtesy Wellcome Trust Medical Photo Library

The Tsetse fly is the biggest of all bloodsucking flies, growing up to 15mm.The flies themselves do not cause the disease, but when the flies bite humans and other animals they introduce tiny parasites called trypanosomesinto the bloodstream . What happens next is that trypanosomes proliferate and gradually invade all the organs of the host.

In advanced stages of disease, the parasite invades the central nervous system. The patient’s behaviour changes; they can no longer concentrate and become indifferent to their environment. Sudden and unpredictable mood changes become increasingly frequent, giving rise to lethargy with bouts of aggressiveness. Patients are overcome by such extreme torpor that eating, speaking, walking or even opening the eyes call for an unsurmountable effort. At night they suffer insomnia and during the day are exhausted by periods of sleep-like unconsciousness. Finally, patients fall into a deep coma and die.

One of the drugs used for treatment, Melarsoprol, contains arsenic and kills one in twenty patients. Without treatment, the sleeping sickness will lead to death.

The tsetese fly is so deadly that scientists have taken drastic measures to exterminate the fly population. This involves breeding hundreds of millions of male flies, sterilising them with gamma radiation and releasing them into the bush from low-flying aircraft. Tsetse fly females breed only once, so if the male is sterile the population collapses. 

Tiny but deadly.

The humble dung beetle , destined for a lifetime of shit has now expanded its diet to include chomping on live millipedes!

Scientists from Peru have recently discovered a particular species of dung beetle (Coleoptera: Scarabaeidae), Deltochilum valgum, which is the first of its kind to display predatory behaviour, using its modified head and sharper “teeth” to decapitate live millipedes and slice up ther rest of the body for feeding.

Using infrared cameras, the research team led by Dr. Trond Larsen were able to catch live footage of the nocturnal dung beetles in action. Dung beetle heads are normally flat and shovel-like, useful for burrowing in a dung pile. However, D. valgum has a much narrower and pointy head, adapted to get inside the millipede’s body and feed on its insides. The sharper ‘teeth’ they posses are also useful in severing the head of the millipedeand cutting up the body into smaller pieces.

Talk about ferocious!

watch?v=VjLfcHTwr6E
Supplementary material video accompanying Biology Letters article ‘From coprophagy to predation: a dung beetle that kills millipedes’.
Such behaviour intrigues scientists as there is a huge jump from coprophagy (dung feeding) to carnivory. They hypothesise that this unusual evolutionary transition was driven by the high levels competition for food.

This extraordinary behaviour of carnivorous dung beetles is certainly one which will change the way we view the humble dung beetle!
For more information:

Larsen, T., Lopera, A., Forsyth, A. & Genier, F. 2009. From coprophagy to predation: a dung beetle that kills millipedes. Biol. Lett. 5 : 152-155

BBC News “Little dung beetle is big chopper”. Accessed 8th April 2009. (http://news.bbc.co.uk/2/hi/science/nature/7840404.stm)