Zool 406 - Caecillians

How many families are in gymnophiona?

5-7 Families

What is the morphology of Caecillians?

• Blunt, bullet shaped heads

• Long cylindrical bodies

• No limbs

• No tails, or very short tail

• Grooves = primary annuli; metameric

• Secondary and tertiary annuli may be present

• Dermal scales may be present

What are some adapatations to a fossorial lifestyle in caecilians?

• Compact head; no fenestrations

• Degenerate eyes

• No ear openings

• Underhung jaws

• Limbs and girdles completely lost

What kind of locomotion do caecilians use?

Serpentine + Concertina

Where are caeciliasn found worldwide?

• Tropical & World wide; except Madagascar and Papua-Australia

• Little is known about biology; most info comes from captive or dead specimen

T/F all Caecilians have external fertilization?

False

How are muscles arranged in caecilians for locomotion?

• Crossed-helical array of tendons surrounding body cavity

• 2X forces of similar-sized fossorial snakes with longitudinally oriented muscles

What is the general arrangement of caecilian sensory systems?

Olfaction via nose and vomeronasal organ

Accessory chambers extend off laterally and ventrally; includes vomeronasal

External naris → Large olfactory cavity → Choana (internal naris)

What does the olfactory cavity look like in Salamanders?

Relatively simple;

• Main cavity partially divided by ventrolateral fold.

• Aquatic forms have a small nasal cavity and a large vomeronasal organ.

What does the olfactory cavity look like in Frogs ?

Complex nasal caviy;

• Large vomeronasal organ

What does the olfactory cavity look like in Caecillians ?

Simple nasal cavity;

• Near complete separation of nasal and vomeronasal cavities

• Major modification = sensory tentacle

T/G the sensory tentacle is an apomorphy of gymnophonia?

True

What does the sensory tentacle of Caecilans look like?

• Paired

• Emerge from cavity on side of snout; between eye and nostril

• Derived from tear duct, certain extrinsic eye muscles and other eye parts

• Connected to vomeronasal organs

• Tentacular sheath; flexible and non retractable

What abilities does the sensory tentacle have?

• Chemosensory

• Mechanosensory

• Olfactory

What do the eyes look like in caecilians?

• Lidless, reduced and function to detect changes in light intensity only

• Fixed in bony sockets, covered by skull bones or lacking

How are the eyes and tentacle distinct in Caecilians?

They reside in unique locations in the skull

What organ is used for internal fertilization in caecilias?

The Male phallodeum which is eversible

It is midsized with tuberosities, ridges, grooves and crests

What are some examples of the diversity in reproductive styles in Caecilians?

• Egg layers

• Aquatic larvae

• Direct development

• Viviparity

What are some examples of parental care in Caecilians?

1. Egg layers guard eggs

2. Direct developing species receive post-paritive maternal care; provision of some nutrition

3. Viviparous species can have skin feeding