Diversity of Living World and Animal Kingdom
Diversity of Living World and Animal Kingdom tests classification as evidence-based reasoning. You must place an animal using body-plan features and write scientific names correctly, not simply recall a list.
Core rules
- Binomial nomenclature: genus capitalised, species lower case, both italicised; authority abbreviated and not italicised.
- Hierarchy: Kingdom, Phylum, Class, Order, Family, Genus, Species.
- Body-plan criteria: cellular organisation, symmetry, germ layers, coelom, segmentation, notochord.
- True coelom is lined by mesoderm; pseudocoelom is partly lined; acoelomate animals have no body cavity.
- Porifera and Cnidaria are diploblastic; Platyhelminthes onward are triploblastic.
- Chordate hallmarks: notochord, dorsal hollow nerve cord, pharyngeal gill slits, post-anal tail.
Worked example
A marine animal is sessile as an adult and has calcareous plates, tube feet and a water vascular system. Its adult symmetry is radial, but its larva is bilateral. Identify the phylum.
Reasoning: tube feet and the water vascular system are unique to Echinodermata. Calcareous ossicles and a bilateral larva confirm it. Radial adult symmetry alone might suggest Cnidaria, but cnidarians are diploblastic, lack tube feet and possess cnidoblasts. Answer: Echinodermata.
Traps that cost marks
- Radial adult symmetry does not make echinoderms diploblastic; they are triploblastic coelomates.
- A pseudocoelom is not a true coelom; do not label Ascaris as coelomate.
- In adult vertebrates the notochord may persist only as remnants; vertebrates are still chordates.
- Do not underline or capitalise the species epithet.