Jan 6, 2012

Ryukyu Land Leech (Taipei)

English Name: Ryukyu Land Leech, Ryukyu Mountain Leech
Scientific Name: Haemadipsa rjukjuana
Chinese Name: 琉球山蛭 (liu2 qiu2 shan1 zhi4)  
Chinese Meaning: "Ryukyu Mountain Leech"

Ryukyu Land Leech (Haemadipsa rjukjuana)
Date: October 24, 2011
Location: Maokong Yuanshan, Wenshan Districty, Taipei City 
Coordinates: 24° 58' 8" N, 121° 36' 04" E

Taiwan is a paradise for nature walks, but hikers sometimes have to deal with the nuisances of the tropical forest - mud, mosquitos, and leeches. Contrary to popular belief, not all leeches are bloodsuckers. Some of these earthworm-relatives in fact prefer to hunt small prey that they can swallow whole, such as worms or small snails. Of those that do feed on blood, most in fact do not attack humans, instead preferring to attach to water snails, fish, and frogs. However, Myth #2 about leeches is less comforting: in reality, not all leeches live in the water. Some species, such as the one pictured here from the land leech family Haemadipsidae, are fully adapted to life on land, waiting on moist plants for a passer-by to provide their next meal.

Foraging Ryukyu Land Leech (Haemadipsa rjukjuana) with body
extended (left) and contracted (right)

This leech species is named after the Japanese Ryukyu Islands just northeast of Taiwan, and is also found in much of Southeast Asia. It's an active hunter, spending its time near the forest floor, waiting for large mammals like humans or dogs to come near. It has a disconcerting habit of stretching its body up off the ground and waving its head around in the air, searching for a meal using its complex sensory system, which can detect changes in vibration, airflow, brightness, and temperature. Once it zeroes in on a target, it crawls inchworm-style along the ground or vegetation, then up onto the body of the new host, looking for areas of soft skin to bite into. Although it has no problem moving on land, it does require a moist environment, and it can usually be avoided by making sure not to brush your feet up against wet plants.

Ryukyu Land Leech (Haemadipsa rjukjuana) feeding on human blood.

As a kid, I always thought that leeches drank blood using big suckers on their heads. However, I recently learned that the large sucker on the fat end of the leech is actually its tail (seen on the right in the photo above), which it uses to hang on while it feeds with a much smaller sucker on the small end, which is actually its head (seen on the left). The dried blood on the far right of the photo is from a separate bite, inflicted by the leech from the first photo. You don't feel a thing when the leech bites, but the wound continues bleeding for awhile after it detaches, because of a chemical called hirudin that the creature injects into your blood. The next day, the area swells up into a bump like a mosquito bite, and keeps itching for a week or more. For information on how to remove a leech from your body and treat the bite, see this Wikipedia article.

More photos:


Note: Special thanks for this entry go to a wonderful book called Leech Fauna of Taiwan by Yi-Te Lai & Jiun-Hong Chen. Although it's written for academic audiences, it's a great guide for dedicated amateur naturalists as well. If you're on a tight budget or can't get to a library, most of the information from the book can also be found online at the Biota Taiwanica website (leeches are farther down the list, after all the earthworms).

Dec 2, 2011

White-lipped Tree Frog (Taipei)

English Name: White-lipped Tree Frog, "Brown Tree Frog"*, Brauer's Tree Frog**
Scientific Name: Polypedates braueri (Polypedates megacephalus)**
Chinese Name: 白頷樹蛙 (bai2han4 shu4wa1)
Chinese Meaning: "White-Chinned Tree Frog"

White-lipped Tree Frog (Polypedates megacephalus)
Date: May 24, 2010
Location: Shiyuan Rd., Wenshan District, Taipei City
Coordinates: 24° 59' 24" N, 121° 32' 58" E

One day about a year and a half ago I ran into this tree frog while returning home to our old apartment. It was just sitting there on the sheet-metal wall that separated our driveway from the empty lot next door. I was a bit surprised by its size - it was easy three inches or more from nose to tail. This was my first and only time encountering an adult of this species, though it is reported to be fairly common in Taiwan and China.** A closely related species, Polypedates leucomystax (also sometimes known as the White-lipped Tree Frog), is found throughout most of South and Southeast Asia. Tree frogs in the genus Polypedates are sometimes known as "whipping frogs," apparently due to the masses of foam that they "whip up" to protect their eggs, laid just above areas of standing water. This method of reproduction, which relies on the tadpoles falling or getting washed into the water below, is actually also typical of many other kinds of frogs in the Old World tree frog family Rhacophoridae.

Tadpole of White-Lipped Tree Frog (Polypedates megacephalus)
Date: June 5, 2011
Location: Hemeishan Nature Trail, Xindian District, New Taipei City
Coordinates: 24° 57' 11.6" N, 121° 31' 59.3" E

One year later, I got the chance to see the species in its larval stage while on a walk in the hills a few kilometers away. I discovered one or two tree frog tadpoles swimming in a small pool of water along with a big crowd of the smaller, hexagon-headed young of the Ornate Narrow-Mouthed Frog (Microhyla fissipes (ornata)). Like the adult frog, White-lipped Tree Frog tadpoles are relatively large - this one must have been about two inches long - and they are also recognizable by their dark body color and characteristic white patch at the tip of the snout.

More photos:


*The term "Brown Tree Frog" is often used for both this frog and another species found in Taiwan, Buergeria robusta, not to mention at least one species from elsewhere in the world. To avoid confusion, I have chosen to use another of the common names of Polypedates megacephalus here.

**The native Taiwan variety of this frog has been renamed Polypedates braueri ("Brauer's Tree Frog"). The name Polypedates megacephalus, used until very recently for these frogs in Taiwan, is still in use for the similar frogs found in Hong Kong and southern China. Confusingly, that variety was also introduced to Taiwan in 2006, becoming an invasive species on the island, so now Taiwan has both P. megacephalus and P. braueri. Based on descriptions and distribution maps, I believe the frogs in these photos are the native variety, P. braueri.

Oct 5, 2011

Siamese Rhinoceros Beetle (Orchid Island/Lanyu)

English Name: Siamese Rhinoceros Beetle (Philippine subspecies)
Scientific Name: Xylotrupes gideon philippinensis
Chinese Name: 姬獨角仙 (ji1 du2 jiao3 xian1), 菲律賓姬兜蟲 (fei1 lü4 bin1 ji1 dou1 chong2), 
Chinese Meaning: "Gideon's Single-Horned Fairy", "Philippine Gideon's Dou Bug"

Male rhinoceros beetle (Xylotrupes gideon philippinensis)
Date: August 8, 2010
Location: Road near Yeyin Village, Orchid Island (Lanyu), Lanyu Township, Taitung County
Coordinates: 22° 02' 25" N, 121° 33' 57" E

Orchid Island - also known by its Mandarin name, Lanyu - is an island located just southeast of Taiwan. Though controlled by the Taiwanese government, it is ecologically and culturally a transition area between Taiwan to the northwest and the Philippines to the south. The people here have their own culture and speak a unique non-Chinese language, and the island's ecosystems are home to a number of endemic species. Though not endemic itself, I was delighted to come across this beautiful insect on a night-time walk on Orchid Island last year.

Female rhinoceros beetle (Xylotrupes gideon philippinensis)
Date: August 8, 2010
Location: Road between Dongcing and Yeyin Villages, Orchid Island (Lanyu), Lanyu Township, Taitung County
Coordinates: 22° 02' 52" N, 121° 33' 43" E

This species, which ranges across much of Southeast Asia to Australia, is probably best known to Westerners as the Siamese "fighting beetle", for its role in staged insect fights in northern Thailand and surrounding countries. Apart from bringing in gambling revenue, it is also prized as a pet in many areas. This particular subspecies is limited in range to the Philippines and southeastern Taiwan, and is sometimes known to Taiwanese as the "Lanyu rhinoceros beetle" due to the fact that it is commonly found on Orchid Island, with only much smaller populations existing in other parts of Taiwan. The colloquial Chinese word for "rhinoceros beetle" literally translates as "Single-Horned Fairy" (獨角仙).

Top view: male rhinoceros beetle (Xylotrupes gideon philippinensis)
There are over 300 species of rhinoceros beetle worldwide, most of which share a similar life cycle: a year or more spent underground as a grub eating rotting wood, followed by a 2-4 month long adult life of mating and feeding on fruit and nectar. Despite its reputation as an aggressive fighter in the ring, the Siamese rhinoceros beetle is harmless to humans, and relies on its ability to produce a hissing noise to scare away large predators. Unfortunately, hissing won't protect it from the growing number of motor scooters in use on Orchid Island's roads, where it makes itself vulnerable by coming out to mate under the street lights from May to August.