Top Tweets for #Octapoda

about 2 years ago

#Argonauts (#Argonautidae, #Octapoda) are a group of #octopuses that, like the Nautilidae, have a coiled #shell made of lime on their bodies. However, there is no close relationship between these two cephalopod groups. The #calcareous skeleton of octapods has been completely lost through #evolution. The shell at argonauts is a secondary new development. It is therefore called a #pseudoconch and is not firmly attached to the animal's body. Instead, the shell is held in place with the arm ring placed over the body and the arm suction cups attached to it. The building material for the shell is secreted by glands in the distal area of the first pair of arms. Unlike Nautilus, the shell of Argonauts is very thin and is not made of #aragonite, but of #calcite. The shells of Nautilidae and Argonautidae therefore do not meet any #homology criteria. The shell of the Argonautidae is only worn by females because its function is to transport and protect the egg deposit. In addition, the shell performs a similar (#analogue) function to that of Nautilus. The authors J. K. Finn & Mark D. Norman (2010) have confirmed that the female Argonauts actively fill their shells with air on the water surface when necessary in order to generate the necessary #buoyancy to be able to float in the desired water layers. © #StefanFWirth, Berlin 2024 References: J. K. Finn & Mark D. Norman (2010): https://t.co/mfkX8fF1j6 A short video file on X on "takuya pro diver" : https://t.co/ZfMrevHbZB Photos: 1) Female #Argonauta #argo with severely damaged eggcase and eggs, encountered at a depth of about 20 cm in a cove at the southern coast of Turkey. Original uploader was Bernd Hofmann, 2007, licensed under creative Commons https://t.co/QvN9f7YYc6 2) Argonauta argo, Comingio Merculiano (1845–1915) in Jatta Giuseppe, in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or fewer. https://t.co/1AODSNJi6D

wirthstef's tweet photo. #Argonauts (#Argonautidae, #Octapoda) are a group of #octopuses that, like the Nautilidae, have a coiled #shell made of lime on their bodies. However, there is no close relationship between these two cephalopod groups. The #calcareous skeleton of octapods has been completely lost through #evolution. The shell at argonauts is a secondary new development. It is therefore called a #pseudoconch and is not firmly attached to the animal's body. Instead, the shell is held in place with the arm ring placed over the body and the arm suction cups attached to it.

The building material for the shell is secreted by glands in the distal area of the first pair of arms. Unlike Nautilus, the shell of Argonauts is very thin and is not made of #aragonite, but of #calcite. The shells of Nautilidae and Argonautidae therefore do not meet any #homology criteria. The shell of the Argonautidae is only worn by females because its function is to transport and protect the egg deposit. In addition, the shell performs a similar (#analogue) function to that of Nautilus. The authors J. K. Finn & Mark D. Norman (2010) have confirmed that the female Argonauts actively fill their shells with air on the water surface when necessary in order to generate the necessary #buoyancy to be able to float in the desired water layers.

© #StefanFWirth, Berlin 2024

References:

J. K. Finn & Mark D. Norman (2010): https://t.co/mfkX8fF1j6

A short video file on X on "takuya pro diver" :
https://t.co/ZfMrevHbZB

Photos:
1) Female #Argonauta #argo with severely damaged eggcase and eggs, encountered at a depth of about 20 cm in a cove at the southern coast of Turkey. Original uploader was Bernd Hofmann, 2007, licensed under creative Commons https://t.co/QvN9f7YYc6
2) Argonauta argo, Comingio Merculiano (1845–1915) in Jatta Giuseppe, in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or fewer.
https://t.co/1AODSNJi6D

takuya pro diver

@takuya_sea

about 2 years ago

海の生き物の知識が少しでもあれば一生に一度は見てみたい！！というクラスの珍しいタコブネ定置網にかかり、漁師さんがご厚意で保護してくれたみたいです。超感謝。多分エマワトソンくらい会えないと思う。

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Top Tweets for #Octapoda

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