Autumnwatch 2020 episode 4: Autumnwatch is inspired by Halloween. Gillian shows off the amazing hydraulic power of spiders’ legs. Iolo has an exclusive update on the remarkable story of a giant vulture.
Iolo has an exclusive update on the remarkable story of a giant vulture that set up home in Derbyshire! Megan and Chris look back at the mouse experiment and their friendly foxes, and Michaela catches up on the highs and lows of the Scottish seal colony.
BBC’s popular wildlife programme records the changes in nature across four days in autumn, using a network of cameras to track the action in real time, including never-filmed-before behaviour, as animals prepare for their toughest time of the year. Presenters anchor `Autumnwatch’ from a different base each year, and camera teams are spread throughout the UK, showcasing the beauty of iconic wild places and revealing new and surprising wildlife stories as they happen.
Autumnwatch 2020 episode 4
Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms.
Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every habitat with the exceptions of air and sea colonization. As of July 2019, at least 48,200 spider species, and 120 families have been recorded by taxonomists. However, there has been dissension within the scientific community as to how all these families should be classified, as evidenced by the over 20 different classifications that have been proposed since 1900.
Anatomically, spiders (as with all arachnids) differ from other arthropods in that the usual body segments are fused into two tagmata, the prosoma, or cephalothorax, and opisthosoma, or abdomen, and joined by a small, cylindrical pedicel (however, as there is currently neither paleontological nor embryological evidence that spiders ever had a separate thorax-like division, there exists an argument against the validity of the term cephalothorax, which means fused cephalon (head) and the thorax.
Similarly, arguments can be formed against use of the term abdomen, as the opisthosoma of all spiders contains a heart and respiratory organs, organs atypical of an abdomen). Unlike insects, spiders do not have antennae. In all except the most primitive group, the Mesothelae, spiders have the most centralized nervous systems of all arthropods, as all their ganglia are fused into one mass in the cephalothorax. Unlike most arthropods, spiders have no extensor muscles in their limbs and instead extend them by hydraulic pressure.