Star Nosed Mole
No description yet. This curated deck is ready for daily study.
Card preview (21)
Why is it important for the star-nosed moles to be fast hunters?
• they share their tunnels with other animals and must out compete for food
In general what are the star-nosed moles interesting adaptations?
• special mechanosensory abilities to catch and eat prey in under 1/5 s • swim well and smell underwater by blowing bubbles and breathing them back in
How does the Eastern mole differ from the star-nosed moles?
• star-nosed mole has a pebbled, star-shaped nose with tentacles
What is an eimer’s organ?
• domed epidermal sensory organ containing merkel cells, encapsulated corpuscles (similar but smaller than pacinians corpuscle), and circle of free nerve endings
What animals have eimer’s organs?
• most species of talpids - the ones that don’t live in dry habitats and were most likely degenerated due to harsh soil conditions
What are the three types of sensory cell?
• primary sensory cells: cell bodies at surface, receive input and send it down a fiber • secondary sensory cells: cell bodies at surface, transmit info to nerve cell • sensory nerve cell: cell body below surface, send dendrites to the surface
What type of sensory cell are somatosensory cells?
• sensory nerve cells - cell body below surface and send dendrites up
What characteristics does processing of somatosensory take into account?
• threshold and distribution - stimulus strength (measured by firing rate)
What sensations are merkel cells good at detecting?
• steady pressure and intensity • slow adapting • small defined receptive field • numerous/high density • firing increases for a smaller object • good for determining fine spatial detail, localization and texture
What sensations are pacinian corpuscles good at detecting?
• vibration and acceleration • rapidly adapting (fire at start and end of stimulus) • large receptive fields
What experiments have been conducted to examine threshold and distribution of mechanosensory cells?
• von fray hair: poke skin with hair just until it bends • stimulation with an electric rod • indentation depths to measure threshold
What experiment has been conducted to examine stimulus strength?
• pushed rod into hairless part of cats foot - for stronger stimulus, more firing occured
What is the difference between hairless and hairy skin?
• merkel cells are closer to the surface for hairy skin
What are free nerve endings useful for detecting?
• determine texture and differentiate between a smooth pebble and segmented worm based on the deflection of cell columns and which nerve terminals are maximally stimulated • lateral free nerve endings: nociceptors to determine if mole has entered environment with abrasives
If a star nosed mole thinks it has encountered food, what is it sure to do?
• make contact with its 11th appendage
How does the family Talpidae have similarities?
• all have poor eyesight but mechanosensory specializations - gather tactile information by probing environment with tip of snout (rhinarium)
How do the eimer’s organs for star nosed moles compare to the rest of the family?
• rounder, smaller and more organized
What does the star-nosed moleunculus look like?
• large nose and tentacles and large front paws - large amount of somatosensory cortex is devoted to processing this info
For rats, what kind of mapping occurs in the cortex where sensations from the whiskers are processed?
• topographic arrangement of barrels/whisker fields in cortex that correspond to the spatial arrangement of the whiskers
How are the star-nosed moles noses mapped in the cortex?
• tentacles of nose are mapped in a ray-like pattern that matches the location of the actual tentacles in regards to each other • mapped three times in primary sensory, secondary sensory, and caudal-lateral cortex
What can be determined by looking at mole fetuses?
• the sensitive upper and lower appendages have a head start in development • gestation takes 30 days and the star nose develops in the third and fourth week • in development they look similar to coast moles before the appendages peel forward and open up