Review any comments regarding my addition on the talk page
Add the rest of draft to Turtle page, taking care to correctly transfer the citations
Neck expansion creates suction when the head is thrust forward and the oropharynx is expanded, and this morphology suggests the retraction function is for feeding purposes as the suction helps catch prey.[1] The protection the shell provides the head when it is retracted is therefore not the main function of retraction, thus is an exaptation.[2] As for the difference between the two methods of retraction, both Pleurodirans and Cryptodirans use the quick extension of the neck as a method of predation, so the difference in retraction mechanism is not due to a difference in ecological niche.[3]
This image from Pacific Lutheran University shows the cervical vertebrae of a Cryptodira as seen ventrally. The vertebrae have an S-shaped curve to allow for neck retraction into the shell.Addition of second image in hopes both images can be complementary in understanding the cervical vertebrae structure, which in turn explains the function of the neck.
Conferring with Yelena to decide what should be said between our two drafts and what should initially be edited into the turtle article(s):
Initial addition:
" The mechanism of neck retraction differs phylogenetically: the suborder Pleurodira retracts laterally to the side, anterior to shoulder girdles, while the suborder Cryptodira retracts straight back, between shoulder girdles.[4] "
On Turtle page, remove the initial sentence in neck retraction and replace with this ^
" Since these vertebrae are not fused and are rounded, the neck is more flexible, being able to bend in the backwards and sideways directions.[4] The primary function and evolutionary implication of retracting the neck is thought to be for feeding rather than protection.[5] Neck retraction and reciprocal extension allows the turtle to reach out further to capture prey while swimming. "
Image uploaded in Week 10 along with draft. It shows the cervical vertebrae in a Cryptodira, indicating the linear method of neck retraction. The image was my own, uploaded to the Commons of Wikipedia and now available for usage within Wikipedia.
Different species of turtles have two different methods of retracting their heads and necks. The mechanism of neck retraction differs phylogenetically: the suborder Pleurodira retracts laterally to the side, anterior to shoulder girdles, while the suborder Cryptodira retracts straight back, between shoulder girdles.[4] These differences have different structures to allow for the function, but the function of retraction for is made possible by the independent individual cervical vertebrae.[6] Since these vertebrae are not fused and are rounded, the neck is more flexible, being able to bend in the backwards and sideways directions.[4] The primary function and evolutionary implication of retracting the neck is thought to be for feeding rather than protection.[5] Neck retraction is a neck extension adaptation so the turtle can reach out further to capture prey while swimming. In pleurodires, neck expansion creates suction when the head is thrust forward and the oropharynx is expanded, and this morphology suggests the retraction function is for feeding purposes.[1] The protection the shell provides the head when it is retracted is thus an exaptation.[2] As both Pleurodirans and Cryptodirans use the quick extension of the neck as a method of predation, the difference in retraction mechanism is not due to a difference in ecological niche.[3]
The cervical vertebrae of a Cryptodira turtle shown here. The vertebrae curve inward as the neck is retracted.
The image to the right shows the cervical vertebrae of a Cryptodiran turtle. The vertebrae are able to curve inward in an S-shape as the head and neck retracts.
There was a consensus of concern regarding Yelena and I both being interested in neck retraction. Suggested solutions for this encouraged Yelena and I to focus on separate implications of the neck retraction. After discussing our options and debating whether one should switch to a different topic, we decided that we would follow the advice of our peers and have different focuses. Thus, Yelena will look at the morphological intricacies of the turtle vertebrae and I will study the ecological and evolutionary intricacies. We will be able to confer some relationships between structure and function, but for the most part Yelena will be in charge of structure and I will worry about function. I will use this week to expand the sources I have for further focus, clarity, and differentiation of my vs. Yelena's sections. This means differences in ecological niches between Cryptodira and Pleurodira, as well as the different evolutionary processes that led to the current separate mechanism. I hope to find if there are any differences in diet and/or habitat between the two, and what the differences present mean.
As far as structure is concerned, a couple of responses expressed dissatisfaction in the sources provided and citation, so I will go over the citations again and try to clean them up. Additionally, concern for the images was voiced, which can only lead me to restate our plans of uploading our own images from the dissections and models in lab.
Overall good draft! The information presented seems to be supplementary and easy to understand.
Draft 1: Sexual Dimorphism
Regarding grammatical flow of the sentences, the second sentence uses "which" twice, making it sound redundant. Otherwise well structured.
Draft 2: Sexual Dimorphism of lungs
Good information and sources! The information discrepancy is something to be aware of, perhaps posing a question on the Salamander talk page would help sort some of the confusion. For the lungs vs. skin respiration, do these mechanism occur simultaneously or is there a specific stage in the life cycle that features one above the other? Additionally, an expansion on body expansion and compression would be helpful, explaining what the expansion/compression entails.
Draft 3: Jaws
Good structure, flow, and information! Specifying more obviously which method is strike and which is stationary would help keeping the mechanisms clearly separate.
Draft 4: Food Habits
Consider rewording the last two sentences, as they are somewhat difficult to follow and there seem to be wording mistakes. As far as content goes, do the sources specify further the implications of the animals eaten beyond crawfish not returning the amount of energy expended? How else do different environments affect the food habits? Are there any special feeding mechanics unique to amphiuma? (<- this could be worked together with the jaws)
Sources defining the mechanism behind why some are toxic and some are nontoxic?
Swim Bladder
Sentence two: specify that "they" means the fish itself. Additionally, how is aerial breathing rate significant? The next sentence could be better tied into the second if specified that aerial breathing is crucial for hypoxic aquatic environments.
Anatomy
Establish the importance/significance of having paired appendages.
Distribution
Concise while outlining general geographic range. Good idea of creating an original image to then be uploaded!
Overall, good range of information to be added. More sources and information could help bring more to the article(s), but what is already addressed looks to be good additions.
Structural analysis of neck retraction: muscles, vertebral movement, etc.
How other structures (esophagus, larynx, trachea, etc.) are affected when neck retracts
Emydidae page: mention the suborder Cryptodira and its significance to neck retraction
In the article Turtles, there are a lot of opportunities to supplement information regarding neck retraction. The methods of such differs phylogenetically: the suborder Pleurodira retracts to the side, anterior to shoulder girdles, while the suborder Cryptodira retracts straight back, between shoulder girdles.[4] These differences have different structures to allow for the function, and the function of retraction is made possible by the independent individual cervical vertebrae.[6] Since these vertebrae are not fused, the neck can bend in the backwards and sideways directions. The primary function and evolutionary implication of retracting the neck is for feeding rather than protection, which is not discussed in the article.[5] Neck retraction was more of a neck extension adaptation so the turtle could reach out further to capture prey while swimming. In pleurodires, neck expansion creates suction when the head is thrust forward and the oropharynx is expanded, and this morphology suggests the retraction function is for feeding purposes.[1] The protection the shell provides the head when it is retracted is thus an exaptation.[2]
The sources used to review the function of neck retraction did not include cryptodira, but hopefully further research will elaborate further. In addition, the CC image search did not reveal very many images representing the anatomy of a turtle neck, so uploading pictures taken during dissection will be the best way to add images.
Week 5: Turtle Article Sources for Neck Retraction
pleurodires horizontally fold, which does not provide more protection than the lateral folding of the Cryptodira, thus it is inferred that the mechanism of head retraction is for feeding purposes more so than for protection.
Protection is an exaptation, primary function is to catch prey
Kinematics and functional morphology of aquatic feeding in Australian snake-necked turtles (Pleurodira; Chelodina)[1]
I am intrigued by the turtle's ability to breathe in two separate ways and would like to physically learn the concept of an organism living in a shell.
There are only two sentences briefly mentioning turtles on the Scute page that could use elaboration.
A cephalochordate (from Greek: κεφαλή kephalé, "head" and χορδή khordé, "chord") is an animal in the chordatesubphylum, Cephalochordata. They are characterized as chordates, as they possess the 5 characteristics, also known as synapomorphies, of all chordates during a point of the larval stages or adulthood. These synapomorphies include: notochord, dorsal hollow nerve cord, endostyle, pharynx and post-anal tail. Cephalochordates are represented in modern oceans by the Amphioxiformes (lancelets, also known as amphioxus). Along with its sister phylum, Urochordata, Cephalochordata can be classified as belonging to the taxon Protochordata.
The second and third sentences: I updated the definition so it was correct (the synapomorphies are not necessarily present from larval stage all the the way through adulthood, thus was fixed). Additionally, I added links to synapomorphies, the word and four of the five actual characteristics (post-anal tail did not have a link available). Some of the wordings were updated so the sentence flowed better.
The anatomical structures are referenced but not described
Untrue: the five synapomorphies are not found throughout adulthood. Also, doesn't define them as synapomorphies
Outdated sources (2002 and 2006), incomplete bibliographies (#3) and lack of links to source
More links would be helpful
Could add and expand: location, reproduction, feeding section
Make fossilized species its own section, separate the extinct from the extant
Poorly labeled image, no citation
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