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Parental Care In Amphibia. Dr. Rashmi Tripathi Department of Zoology Brahmanand College, Kanpur. Parental Care In Amphibia :
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Parental Care In Amphibia Dr. Rashmi Tripathi Department of Zoology Brahmanand College, Kanpur
Parental Care In Amphibia : In Amphibians there are many devices for the protection during the early stages of development and in this way nature has practiced economy in the number of eggs, which varies in direct proportion to the chances of destruction. Looking after the eggs or the young until they are independent, to defend from predators, is known as parental care. Department of Zoology
It is very important factor for survival Anurams show much grater diversity than urodeles and Apodams The methods of caring by Amphibia generally fall under two broad categories : (A) Protection by nests, nurseries or shelters (B) Direct caring by parents Department of Zoology
Department of Zoology • (A)- Protection by Nests, Nurseries Or Shelters : • (i) Selection of Site – • Many amphibians lay eggs in protected moishland or near water. • Many tree frogs lay eggs not on land but on leaves and branches, overhanging water. eg. Phyllomedusa (South America), Rhacophorus, malabaricus (India), Chiromantis (tropical Africa).
Department of Zoology • Defending territories or eggs – • Males of green frog Rana Clamitans and other species maintain territories to defend eggs. • In mantophyne robusta, male sits over and holds with hands the elastic gelatinous envelope containing eggs numbering 17. • Some tree frog laying eggs above water may sit beside the eggs.
Department of Zoology • (iii) Foam nests – • Many amphibians convert mucons secretions into nests for their young. • In Jpanees tree frog, Rhacophorous Schlegeli, the mating couple digs a hole or tunnel into which eggs are left in frothy mass. • Female of South America tree frog, Leptodactylus mystacinus lays eggs in frothy mass of mucons. • Some anurams lay eggs in nests of foam floating on water Foam Nest
Department of Zoology • (iv) Mud Nests – • A large tree frog, Hylafaber known in Brazil as the “Ferreiro”. The male digs a little hole or nursery in mud, in which the female lays her eggs. • The nest is 30 cm in diameter and 5 to 8 cm deep. • Tadpole hatch within this and develop until they are large enough to defend themselves. Mud Nest
Department of Zoology • (v) Tree nests – • The South American tree frog,Phyllomedusa hypochon drales, lays eggs in a folded leaf nest with margins glued together by cloacal secretion. The tadpoles when formed fall directly into water below. • Tree frog, Hyla resinfectrix lives a shallow tree cavity with bees wax obtained from the lives of certain stingless bees. Female lays eggs when the cavity is filled with water. Tree Nest
Department of Zoology • (vi) Transparent gelatinous bags, in water – • The eggs of Phrynixalus biroi are large which are enclosed in transparent common membrane secreted by female and is left in the mountain streams. • A small aquatic salamander, Salamandrella keyserlingi deposits 50 to 60 small eggs in a gelatinous bag.
Department of Zoology • Direct development – • In some terrestrial or tree frogs, the eggs hatch directly into little frogs thus avoiding larval mortality, e.g., Eleutherodactylns, Arthroleptis, Hylodes and Hylanebulosa. • In Red backed salamander, Plethodon cirereus, the hatchlings are miniatures of the adults.
Department of Zoology • [B] Direct carrying by parents: • Tadpoles transported from one place to another – • Small South American frogs, Phyllobates and Dendrobates have been observed carrying well developed tadpoles on their back. Tadpole Transported
Department of Zoology • 2. Eggs glued to body – • Many amphibians, carry the eggs glued to their body. • In dusky salamander, Desmo gnathus fuscus, female carries the string of eggs coiled around her neck, until they have hatched. eggs glued to the body
Department of Zoology • In Srilankan tree frog, Rhacophorus reticulatus, the eggs are glued to the belly of female. • In European Midurife toad, Alytes obstericans, when female lays eggs, the male entangles them around his hindlegs. He caries them with him until they are ready to hatch. eggs glued to the body
Department of Zoology • Coiling around eggs – • In Ichthyophis, the female lays large eggs in burrows and carefully guards them by coiling her body around them until they hatch. • Salamander, Plethodon also coils round the eggs which are laid in hollow of the rotton log or beneath a rock. • In Megalobatrachus maximus , male coils around the eggs. Coiling around eggs
Department of Zoology • Eggs in back pouches – • In marsupial frogs or toads, the female carries the eggs on her back, either in an exposed or open oral depression, a closed pouch or individual pockets. (a) Exposed - In a Brazilian tree-frog Hyla goeldii, it is the female which takes charge of the eggs, carrying them on the back. eggs in back pouches
Department of Zoology (b) In common pouch – In Nototrema, the eggs are covered by skin forming a single large brood pouch which opens posteriorly in front of cloacal aperture. (c) In cells like puches – In aquatic Surinam toad, Pipa, skin of female’s back becomes thick, vascular, soft and gelatinous. The eggs are about 100 in numbers and they develop in these pouches.
Department of Zoology • 5. Organs as brooding pouches – • Male of the South American frog, Rhinoderma darwinii, pushes at least two fertilized eggs into his large vocal sacs. After complete development, they emerge out as fully formed froglets. • In West American tree frog, Hylambates breviceps female carries eggs in her buccal cavity. Organs as broody pouches
Department of Zoology • In Arthroleptis, male keeps the larvae in his month. • In Australian frog, Rheobatrachus silus, the female keeps the eggs in her stomach. The tadpoles are expelled through mouth after Metamorphosis. • It is the only known case of gastric incubation in vertebrates.
Department of Zoology • 6. Vivipartiy – • Some anurans are ovoviviparous, they retain eggs in the oviducts and the females give birth to living together. • African toads, Nectophrynoids and Pseudophryne give birth to the little frog. • The European Salamander, Salamandra salamandra produces about 20 small young. • The Apline salamander, S. atra gives birth to one or two fully developed young. • Viviparity is widespread in order by Gymnophiona. Common examples are Typhlonectes, Dermophis, and Geotrypetes etc.
