單孔目Monotremata, 來自希臘 μοvός(monós, “單個”)和 τρῆμα(trêma, “孔”),意思是“單孔”,指這些動物有一個單孔來繁殖(配偶和排卵)和排泄, 該孔一般稱為 “洩殖腔”, 該結構也存在於鯊魚,鰩魚和葉鰭魚,爬行動物和鳥類中. 這種與其他動物類別的強烈相似性表明單孔目是哺乳動物中最古老的種類之一.

Monotremata, from the Greek μονός (monós, “single”) and τρῆμα (trêma, “orifice”), means "one-holed", in reference to the fact that these animals have a single orifice to reproduce (to mate and lay eggs) and excrete, known as “cloaca”, present also in sharks, rays and lobe-finned fishes, reptiles and birds. This strong similarity with other classes of animals denotes how the Monotremata are one of the oldest extant orders of mammals.

種的俗名 Common names of members

針鼴和鴨嘴獸.

Echidna and platypus.

分佈 Distribution 

澳大利亞、塔斯馬尼亞和新幾內亞.

Australia, Tasmania, and New Guinea.

體型 Size 

牠們的體型很小,長度從 30 公分到 50 公分不等.

Their sizes range in small proportions, from 30 cm to 50 cm in length.

形態描述 Morphology

沒有乳頭.雌性通過皮膚上的腺體直接分泌乳汁,排泄在腹部的毛皮上.

針鼴的身體呈圓頂狀,長滿刺,鼻子很長.

鴨嘴獸長著鴨子般的扁平喙和海狸般的尾巴,身體呈棕色扁平桶狀.雄性鴨嘴獸的後腳跟上有鋒利的毒刺.

有助於確定單孔類動物特徵的因素之一是,除了完全沒有牙齒外,牠們的下頜與頭骨的連接方式也不同,這可能與這些動物能夠使用電定位有關.另一個原因是缺乏一種叫做胼胝體的結構,這種結構負責左右大腦半球之間的溝通（在這些動物中,溝通的方式是不同的）.

Nipples are lacking. Females secrete milk from glands directly through the skin and excreted on the fur located on the belly region.

Echidnas have a dome-shaped body covered in spines and a long snout.

Platypus have a duck-like flat bill, as well as a beaver-like tail, with a brown flattened barrel-like body. Males have sharp venomous spurs on the heels of their rear feet.

One of the factors that helps in the characterization of monotremes is the development of a jaw that connects differently to the skull, in addition to a total lack of teeth, possibly associated with the fact that these animals are capable of using electrolocation. Another is the lack of a structure called Corpus callosum, responsible for communication between the left and right cerebral hemispheres (which, in the case of these beings, is done differently).

生態及棲息地 Ecology & Habitat

針鼴：疏林和其他森林環境.

鴨嘴獸：小溪、河流、淺湖、濕地及其河岸邊緣.

Echidna: open forests and other forested environments.

Platypus: creeks, rivers, shallow lakes, wetlands, and their riparian margins.

食性 Diet

針鼴：底層森林中的昆蟲和蠕蟲.

鴨嘴獸：水生無脊椎動物（蝶類、蜉蝣、蜻蜓、豆娘、小龍蝦）.

Echidna: insects and worms from the bottom forest.

Platypus: aquatic invertebrates (caddisflies, mayflies, dragonflies, damselflies, crayfishes).

繁殖  Reproduction 

牠們的繁殖季節在 6 月到 10 月之間,針鼴和鴨嘴獸都採用多雄性交配系統（一只雄性與多只雌性交配,但雌性只與一只雄性交配）.胚珠在輸卵管中受精.胚胎在子宮中發育.然後產下皮蛋.雌性會孵蛋.幼鳥從卵中孵化出來後,會從特殊的乳毛中吮吸乳汁.

Their breeding season is between June and October, with a polygynous mating system (one male mates with multiple females, but females mate with only one male) for both echidnas and platypuses. The ovule is fertilized in the oviduct. Embryo develops in the uterus. Leathery eggs are then being laid. The females will incubate the eggs. After the young hatches from the eggs, they suck milk from special mammary hairs.

已知的物種

Total species known

5

博物館收藏的物種

Species in the collection

2

在香港已知的物種

Species in Hong Kong

0

References 參考文獻

- Bino, G. Kingsfird, R. T., Archer, M., Connolly, J. H., Day, J., Dias, K., Goldney, D., Gongora, J., Grant, T., Griffiths, J., Hawke, T., Klamt, M., Lunney, D., Mijangos, L., Munks, S., Sherwin, W., Serena, M., Temple-Smith, P., Thomas, J., ... Whittington, C. (2019). The platypus: evolutionary history, biology, and an uncertain future. Journal of Mammalogy, 100 (2), 308–327. https://doi.org/10.1093/jmammal/gyz058.

- Opiang, M. D. (2009). Home Ranges, Movement, and Den Use in Long-Beaked Echidnas, Zaglossus bartoni, From Papua New Guinea. Journal of Mammalogy, 90 (2), 340–346. https://doi.org/10.1644/08-MAMM-A-108.1.

- Nicol, S. C., Vanpé, C., Sprent, J., Morrow, G., Andersen, N. A. (2011). Spatial ecology of a ubiquitous Australian anteater, the short-beaked echidna (Tachyglossus aculeatus). Journal of Mammalogy, 92 (1), 101–110. https://doi.org/10.1644/09-MAMM-A-398.1. 

- Griffiths, M. (1978). The Biology of the Monotremes. Academic Press. https://doi.org/10.1016/B978-0-12-303850-0.X5001-0.

- Grant, T. R., Griffiths, M., Leckie, R. M. C. (1983). Aspects of Lactation in the Platypus, Ornithorhynchus anatinus (Monotremata), in Waters of Eastern New South Wales. Australian Journal of Zoology, 31(6), 881 - 889. https://doi.org/10.1071/ZO9830881.