Year 10 Geologists Learn About Ammonites

Year 10 Geologists display some of the fossils in the Stover collection

In a new departure for Stover, 6 Year 10 pupils have taken up the study of Geology this academic year. They are following the WJEC syllabus, and have recently been learning about various fossil groups, including ammonites.





Annie points out an ammonite

Ammonites are an extinct group of marine cephalopod molluscs, which lived in Jurassic and Cretaceous times. Cephalopods (ammonites, nautiloids, octopuses, squids etc.) are the most highly evolved of the molluscs, and in many ways are the most highly evolved of the invertebrates in general (complex eye, large brain etc.). The mouth is surrounded by tentacles, which usually have suckers. Some modern forms have lost their shells (octopus), some have a straight internal shell (cuttlefish, squid) and some still have a coiled external shell (nautilus).

Most ammonites were probably active carnivores and accomplished swimmers. They were able to control their buoyancy by filling the inner chambers of their coiled shells with water or gas through their siphuncle (see diagram). The outside of the shell was often ribbed or keeled in a distinctive way (which is how most fossil species are told apart). Other fossil forms with external shells include: Nautiloids (Cambrian to Recent) and Goniatites (Devonian to Permian).

Ammonite

 

Year 11 Pupils Investigate the Kidney

As part of their GCSE Biology course, Year 11 pupils today investigated the structure of the kidney.

The Dissection Begins

The kidneys are two bean-shaped organs attached to the rear wall of the abdominal cavity. They have a rich blood supply, and as the blood passes through them it is filtered by millions of little structures called nephrons, consisting of: a glomerulus (a coiled ball of capillary blood vessels), and a kidney tubule (of which there are over 1 million, or 60 km worth per kidney).

A Nephron

Finishing Touches

Blood flows into each glomerulus from the renal artery. Small molecules ‘leak out’ under pressure filtration, into the Bowman’s capsule of the tubule. The small molecules are: water, urea, sugar and salt. The urea and most of the water flow down the tubule to a collecting duct and ultimately into the ureter and bladder to be excreted as urine. Useful materials however, like glucose and salt, are actively transported back into the capillaries surrounding each tubule – a process known as selective reabsorption.  

In cross-section, a kidney has two main regions: the outer cortex is lighter coloured, and contains the glomeruli and the beginning and end of each nephron. The inner medulla contains the middle u-shaped part of each nephron (e.g. the loop of Henlé). The medulla extends into the central ‘pelvis’ of the kidney as projections called pyramids.

Kidney in Cross-Section

Kidney Structure

Further Research