Morphological changes, Biology

Assignment Help:

Morphological changes

Regressive changes-These changes include the gradual reduction and ultimate disappearance of all those larval structures or organs that become redundant in adults. The ventral suckers, external gills, the long tail along with fin folds are reabsorbed during early functional life. The peribranchial cavities, the gill clafts are closed; the horny teeth and horny lining of the jaws are lost. The shape of the mouth changes, the cloacal tube shortens and gets reduced. The lateral line organs of the skin of tadpole disappear and some blood vessels are reduced.

Progressive changes-A number of organs and structures become functional during and after metamorphosis. In the anurans these alters are tabulated in Table and include the development of the fore and the hind limbs, the middle ear in connection with the first pharyngeal pouch (the pouch situated among the mandibular and hyoid arches), the tympanic membrane supported through the circular tympanic cartilage. The eye protrudes on the dorsal surface of the head and makes an upper eyelid. The tongue develops from the floor of the mouth.

Remodeling -Some structures and organs that occur and function both before and after metamorphoses, get transformed or remodeled throughout the process in order to meet the requirement of the adult mode of life. These changes, affect primarily the skin, intestine and brain. The skin thickens, and turns into glandular by developing multicellular mucous and serous glands. It also develops an outer keratinized layer also characteristic color and pattern of pigmentation. The brain gets highly differentiated. The intestine that was long and coiled in the herbivorous tadpole shortens and straightens out: Other notable changes which take place are the change in the blood vascular system in order to supply the lungs, the change in the portal system the alteration in the heart as it becomes three chambered from being two chambered earlier.

 


Related Discussions:- Morphological changes

Differences between ecosystems, Some ecosystems possess relatively large nu...

Some ecosystems possess relatively large number of species as compared to others. This is particularly true of tropical forests which exhibit a very rich-biodiversity. For example,

Traditional uses of dung, T r ad i tional Uses of dung Dung has an ...

T r ad i tional Uses of dung Dung has an astonishing and myriad variety of uses which have been developed over a period of time. Dung patties ( gootee ) are mainly used by

Formulate a specific hypothesis, A professor wonders whether good study hab...

A professor wonders whether good study habits lead to better grades in the final exam. Formulate a specific hypothesis and then design an experiment to test it. In your answer outl

Develop a hypothesis relating to the amount, Develop a hypothesis relating ...

Develop a hypothesis relating to the amount of dissolved oxygen measured in the water sample and the number of fish observed in the body of water.

Define oseltamivir, Oseltamivir (Tamiflu)   This oral neuraminidase i...

Oseltamivir (Tamiflu)   This oral neuraminidase inhibitor, started within 36 hours of symptom onset, can decrease the severity and duration of symptoms caused by either influ

Plants - slow moving waters, Plants - Slow Moving Waters Plant life is...

Plants - Slow Moving Waters Plant life is abundant in this habitat and includes rooted vascular plants such as pond weeds and grasses, firmly attached aquatic mosses and multi

Crossing over, is crossing over of chromosomes is a method?

is crossing over of chromosomes is a method?

How to calculate fractional shbrtening, Q. How to calculate Fractional Shbr...

Q. How to calculate Fractional Shbrtening? With the cursor- beam cutting the left ventricle just beyond the tips of mitral valve in an adequate parasternal long axis view,

Developmental biology, a recent topic for my developmental biology assignm...

a recent topic for my developmental biology assignment

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd