Are you a fan of the 19th Century

scientist, Charles Darwin?

If so, this website is for you!  

 

This website aims to draw together key publications, media and websites on Charles Darwin for the enthusiast.

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Darwin & The Roman Snail - Lesson Ideas

1) Discuss the characteristics of Verbascum thapsus (Great Mullein) and

 Verbascum lychnitis (White mullein).  Look at distribution maps of the hybrid.

 

Take a look at examples of  plant and animal 'hybrids' eg. mule as cross of

horse and donkey, liger as cross of tiger and lion, clementine orange as cross

between orange and mandarin; American red wolf as cross of gray wolf and

coyote;  European edible frog as cross  between pool frogs and marsh frogs; zorse as cross between a zebra and horse; Beefalo as a cross of an American bison and a domestic cow;  Perlin as a cross between a Peregrine falcon and Merlin; English bluebell and Spanish bluebell hybrid; loganberry as a cross between the raspberry and blackberry.

 

Ask children to choose two similar species/races/breeds and 'devise' a plant or animal which incorporates features of both of the two species chosen.

 

2) Find and collect empty Garden Snail shells.  Choose some moist materials - eg. cake, sponge, cooked pasta etc.  Weigh small amounts of each, twice.  Place one of the set in the shell (then turn upside down and place on paper) and place the other of the set on a piece of paper.  Leave the 'specimens' for 2-3 days to dry in the air.  Measure the change in weight as an indicator of the loss of moisture from the 'specimens'.  The materials in the shell should have dried out less and therefore lost least moisture.  ie. snail shells protect the body of snails from dehydration.

 

3)  Explore your local grassland/scrub/woodland area for banded snails.  Which snails do you find most of?  Stripy in grassland?  Dull in woodland?  Click here to find out what other people have found out!

 

4)  Snails first appear in the Upper Cambrian period.  Look at the structure of snail shells that lived in the sea millions of years ago.  Look at the range of snail shell shapes that can be found in aquatic snails and terrestrial snails nowadays to see if snail sizes and shapes have changed.

 

5)  Look at the structure/features and lifestyle of Garden Snails. eg. foot muscle, slime, tentacles, eye stalks, eggs in soil, living in damp environments. Look at some live snails.  Watch videos of Garden Snails!

 

6)  Investigate the structure, habitat, seeds, historical uses and myths relating to Scarlet Pimpernel. (Please note that there is a Scarlet pimpernel species and a Blue pimpernel species, but the Scarlet pimpernel sometimes produces blue flowers due to genetic changes in the plant).  Take a look a real Scarlet pimpernels growing in your local area (eg. wasteground).

 

7) Talk about what factors may lead snails to find their way back to a place or to find a new place  (eg. slime trail, memory, smell, eyesight).  To help, read about snails homing instinct! Blindfold some pupils have them led along a route by other children.  Can they find their way back?  Give other children a map of the corridors/classroom/playground and ask them to find their way to different target points. How is it that people have a sense of direction?  Discuss the difference between this and learning to read and acting upon a route from a map.

 

SUMMARY OF LEARNING POINTS IN THE STORY

 

*If two species, such as the Great Mullein and White Mullein, are able to cross-pollinate and produce seed, that offspring is often sterile.  The successful crossing someties results in 'hybrid vigour' where certain characteristics of the plants are exaggerated.

* Animals retain characteristics from their evolution, such as the anail being tolerant of salt water (for short periods), which make them tolerant of a variety of conditions.  This means they are more 'adaptable'.

* In populations of plant and animal species  'out of the ordinary', 'from the norm' characteristics can appear within individuals.  (In the case of the Scarlet Pimpernel, plant pigments relating to the colour of the flowers, are produced by a series of enzymes, each of which will be coded for by a different gene.  Genetic variants that disrupt enzyme activity can result in different pigments or cobinations of pigments being produced, leading to different flower colours ie. the blue coloration).

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