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[[Category:Echidna]] [[Category:Animal Development]]
[[Category:Echidna]] [[Category:Monotreme]] [[Category:Australia]] [[Category:Animal Development]]

Revision as of 18:57, 23 August 2012

Introduction

Echidna

The Echidna family consists of 2 major groups the short-beaked in Australia and long-beaked in New Guinea and Indonesia (Irian Jaya). Together with the platypus these are the only 3 surviving genera of the order Monotremata.


Echidna egg ultrasound [1]

The echidna is a unique egg-laying mammal, the embryo is referred too as a "puggle" (not to be confused with the dog breed, produced by mating a Pug with a Beagle) and is not a common animal model of mammalian embryonic development.

The New Guinea long-beaked echidna (Zaglossus bruijni bartoni) is currently on the endangered category (More? Zoo Threatened Species list)


Links: Echidna | Koala | Platypus | Historic - Monotremata and Marsupialia Embryology | Category:Echidna

Some Recent Findings

  • Monotreme ossification sequences and the riddle of mammalian skeletal development[2] "Late femoral ossification with respect to tibia/fibula in monotremes and moles points toward developmental integration of the serially homologous fore- and hindlimb bones. Monotreme cervical ribs and coracoids ossify later than in most amniotes but are similarly timed as homologous ossifications in therians, where they are lost as independent bones. This loss may have been facilitated by a developmental delay of coracoids and cervical ribs at the base of mammals. The monotreme sequence, although highly derived, resembles placentals more than marsupials. Thus, marsupial postcranial development, and potentially related diversity constraints, may not represent the ancestral mammalian condition."
  • Hibernation and reproduction overlap in the echidna. [1] "During hibernation there is a slowing of all metabolic processes, and thus it is normally considered to be incompatible with reproduction. ... The mating of males with torpid females is the result of extreme competition between promiscuous males, while re-entry into hibernation by pregnant females could improve the possibility of mating with a better quality male."
  • Characterisation of monotreme caseins [3] "...Overall, the conservation of the genomic organisation of the caseins indicates the early, pre-monotreme development of the fundamental role of caseins during lactation. In contrast, the lineage-specific gene duplications that have occurred within the casein locus of monotremes and eutherians but not marsupials, which may have lost part of the ancestral casein locus, emphasises the independent selection on milk provision strategies to the young, most likely linked to different developmental strategies. The monotremes therefore provide insight into the ancestral drivers for lactation and how these have adapted in different lineages."
  • Monotreme olfactory tubercle[4] "... The small olfactory tubercle region in the platypus is consistent with poor olfaction in that aquatic mammal, but the tubercle in the echidna is more like that of a microsmatic mammal than other placentals occupying a similar niche (e.g., insectivores)."
  • Sensory trigeminal nuclei of the echidna, platypus and rat.[5] "..... Our findings indicate that the trigeminal nuclei of the echidna do not appear to be highly specialized, but that the principal, oralis and interpolaris subnuclei of the platypus trigeminal complex are highly differentiated, presumably for processing of tactile and electrosensory information from the bill."

Taxon

Short-beaked Echidna - Tachyglossus aculeatus

Long-beaked Echidna - Zaglossus bruijni

Tachyglossus aculeatus Lineage (full) cellular organisms; Eukaryota; Fungi/Metazoa group; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Mammalia; Prototheria; Monotremata; Tachyglossidae; Tachyglossus

Echidna Zaglossus bruijn Lineage (full) cellular organisms; Eukaryota; Fungi/Metazoa group; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Mammalia; Prototheria; Monotremata; Tachyglossidae

Development Overview

Gestation is from 22 to 23 days. (based upon 20 observed matings and documenting 30 incidences of egg laying, Rismiller, 1999).

Egg only a single egg is generally laid.

Incubation lasts for approximately 10 days after laying, the hatched embryo (puggle) requires further development.

Embryo after hatching hangs from hairs and succles from a "mammary gland" (mammary hairs) in the pouch for approximately 50 days and continues to develop.

Echidna historic embryology 01.jpg Echidna historic embryology 02.jpg

Historic drawings of Echidna embryology (1894).[6]

Evolution

The oldest platypus and its bearing on divergence timing of the platypus and echidna clades.[7]

"Monotremes have left a poor fossil record, and paleontology has been virtually mute during two decades of discussion about molecular clock estimates of the timing of divergence between the platypus and echidna clades. ...Strict molecular clock estimates of the divergence between platypus and echidnas range from 17 to 80 Ma, but Teinolophos (Early Cretaceous fossil) suggests that the two monotreme clades were already distinct in the Early Cretaceous, and that their divergence may predate even the oldest strict molecular estimates by at least 50%."

References

  1. 1.0 1.1 <pubmed>19562080</pubmed>
  2. <pubmed>21521190</pubmed>
  3. <pubmed>19874726</pubmed>
  4. <pubmed>16244467</pubmed>
  5. <pubmed>16198535</pubmed>
  6. Semon, R. Zur Entwickelungsgeschichte der Monotremen. Denkschriften der Medizinisch-Naturwissenschaftlichen Gesellschaft zu Jena (Embryology of the monotremes. Proceedings of the Medical and Natural Sciences Society in Jena) (1894) 5: 61–74.
  7. <pubmed>18216270</pubmed>

Reviews

<pubmed>14667851</pubmed> <pubmed>14667856</pubmed> <pubmed>14667846</pubmed> <pubmed>11999298</pubmed>

Articles

<pubmed>16435291</pubmed> <pubmed>16244467</pubmed> <pubmed>2048749</pubmed> <pubmed>8103529</pubmed> <pubmed>12476054</pubmed> <pubmed>6864661</pubmed>

Books

The Echidna: Australia's Enigma (Hardcover, 1999), by Peggy Rismiller (Amazon Link) "The oldest surviving mammal on the planet is also one of the most intriguing. Peggy Rismiller, the world's foremost echidna expert, traces the history of this fascinating animal that is native to Australia and New Guinea. A combination of mammal, reptile, and marsupial, echidnas produce milk, but unlike mammals, they are egg-laying creatures and, like marsupials, they have a modified pouch for nurturing their young. This odd animal has two backward-facing appendages and two forward-facing ones. These and other bizarre biological traits are discussed in detail in this thorough guide. Amazing photographs of echidnas enliven Rismiller's text, which includes Aboriginal tribal legends about the animal as well as the latest information on biological research being conducted today. With fossils dating back 120 million years, the echidna lived alongside dinosaurs, but unlike the giant reptiles, it survived. Its story and biology teach a fascinating lesson about endurance, survival, and sustainability."

American Museum Novitates (American Museum of Natural History) Van Deusen, H. M., and G. G. George. Results of the Archbold Expeditions. No. 90. Notes on the echidnas (Mammalia: Tachyglossidae) of New Guinea. American Museum Novitates, 2383:1-23 (1969)

Search PubMed

Search Jan2006 "Echidna development" 303 reference articles of which 20 were reviews.

Search PubMed: Echidna development | monotreme development

External Links

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Cite this page: Hill, M.A. (2024, March 28) Embryology Echidna Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Echidna_Development

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