The University Museum of Zoology, Cambridge (UMZC) runs free clubs for young zoologists to learn about the amazing world of animals. For children aged 6-13 there is a Young Zoologists Club and for those aged 13-18 a new group, the UMZC Zoology Club has been established. The Map of Life team was very pleased to offer an educational workshop to the UMZC Zoology Club, providing teenagers with the chance to learn about convergent evolution using the fantastic collection at the Zoology Museum.
Pondering the tree of life
Before diving in to explore examples of convergence with the specimens at hand, we spent some time considering the tree of life. Bacteria were the first forms of life to evolve, then the eukaryotes – a huge diversity of organisms with their DNA packaged in a nucleus. Among the eukaryotes only three groups evolved to be multicellular, the plants, fungi and animals.
The most primitive animals alive today include sponges, comb jellies, corals and jellyfish, all of which have radial symmetry and only two main body layers. All the other animals typically have three main body layers and bilateral symmetry – a head and tail end, right and left. Over last 10 years or so evidence has crystallised to strongly support the placement of all bilateral animals into one of three major groups, each of which has a rather cumbersome but enlightening name. The ‘deuterostomes’ (e.g. sea urchins and vertebrates) all form their mouth second as the embryo forms its gut, the ‘ecdysozoans’ all moult (e.g. insects and spiders) and the ‘lophotrochozoans’ (e.g. molluscs and annelids) all have a filter feeding apparatus (a lophophore) or a larval stage called a trochophore that spins through water with its hairy, ciliated skirt.
Evolution on Repeat
Armed with an understanding of how organisms are related to each other, we moved on to consider some great examples of plants and animals that have similar features but are in fact from very different branches of the tree of life.
Quickly touching on plants we noticed how succulent desert plants like the ‘Quiver tree’ Aloe dichotoma (right) from African deserts are hard to tell apart from plants which evolved independently in America, in the form of Agave and its relatives such as the ‘Joshua tree’ Yucca brevifolia.
We enjoyed exploring the Museum galleries for vertebrates that had lost (or very much reduced) their limbs in order to adopt a life of burrowing, or in some cases swimming. Among the limbless burrowers and crawlers were the caecilians, related to salamanders in the amphibians, and a number of different reptiles, including worm-lizards (also called amphisbaenians), snakes and modified lizards (e.g. skinks, anguids, pygopodids).
Various reptiles, amphibians and also mammals have arrived at similar solutions to gliding. We found a host of animals that use gliding membranes, including gliding mammals such as colugos and flying squirrels and gliding reptiles such as Draco volans the ‘flying dragon’ and several extinct species. Others glide on membranes between their fingers and toes, such as colourful gliding frogs and gliding geckos.
Watch this Blog for information on future events about the incredible features that creatures have evolved again and again in order to survive and even thrive in deserts, seas, underground and in the air.