Biology 2nd Paper (Zoology) · Classes 11-12 · Chapter 1

Practical: Identifying Vertebrate Specimens.

A specimen is held up and the examiner asks: what is it, which class, and how did you know? The answer needs two things, the classification line and one or two marks that belong to that animal alone. For nine vertebrate specimens, that is exactly what this note gives.

1. Four water specimens

There are nine specimens, in the book's order. For each one you hold two things: its lineage and its identifying features. All nine fall under Phylum Chordata and Subphylum Vertebrata.

The sea lamprey, Petromyzon marinus: Phylum Chordata; Subphylum Vertebrata; Class Petromyzontida; Order Petromyzontiformes; Family Petromyzontidae; Genus Petromyzon. To spot it: a tubular body with no scales and no paired fins. The mouth has no jaws, only sharp horny teeth. There are seven pairs of round gill slits and two dorsal fins.

The shark, Scoliodon laticaudus (earlier named Scoliodon sorrakowah): Phylum Chordata; Subphylum Vertebrata; Class Chondrichthyes; Order Carcharhiniformes; Family Carcharhinidae; Genus Scoliodon. Its body is long and squeezed from the sides, split into head, trunk and tail. The scales are placoid and the tail is heterocercal. The head is flattened top to bottom and ends in a pointed snout, with the mouth on the ventral side. Behind the eyes there are five gill slits on each side, 5 pairs in all.

The figure below shows the shark from the side, head on the left. Tap a chip or a dot to learn the parts.

The taki fish, Channa punctatus: Phylum Chordata; Subphylum Vertebrata; Class Actinopterygii; Order Channiformes; Family Channidae; Genus Channa. Its colour is dark grey with yellow sides and a spotted belly. The long, tubular body is covered with cycloid scales. The head is snake-like and flattened top to bottom. The dorsal and anal fins are long, the pectoral and pelvic fins sit close together, and the tail fin is rounded.

The hilsa, Tenualosa ilisha: Phylum Chordata; Subphylum Vertebrata; Class Actinopterygii; Order Clupeiformes; Family Clupeidae; Genus Tenualosa. The body is bilaterally symmetrical, compressed, shuttle-shaped and shiny silver. The head is large and flattened, and the mouth is terminal. The big eyes are covered by a transparent adipose layer, and the upper jaw has a notch in front. The tail fin is homocercal. Taki and hilsa share Class Actinopterygii, so the class cannot separate them; the marks do.

2. From toad to bat

The common toad, Duttaphrynus melanostictus (earlier name Bufo melanostictus): Phylum Chordata; Subphylum Vertebrata; Class Amphibia; Order Anura; Family Bufonidae; Genus Duttaphrynus. The skin is rough, dry and warty. The body divides into head and trunk. The head carries large raised eyes, nostrils and a tympanum, with a pair of large parotid glands behind the eyes. There are 4 digits on the forelimb and 5 on the hindlimb.

The house lizard, Hemidactylus brookii: Phylum Chordata; Subphylum Vertebrata; Class Reptilia; Order Squamata; Family Gekkonidae; Genus Hemidactylus. The slender body is covered with tiny scales and divided into head, trunk and tail. The triangular head carries the eyes, nostrils and tympanum. There are two pairs of legs, each foot with five padded, clawed digits. The cloacal opening is transverse, and the tail is long.

The magpie robin, Copsychus saularis: Phylum Chordata; Subphylum Vertebrata; Class Aves; Order Passeriformes; Family Muscicapidae; Genus Copsychus. The feathered body is black and white, bluish-grey in the female. The tail is long and slanting, black with white outer feathers. The wings are long, blackish-brown with white marks. The throat and breast are bluish-black.

The guinea pig, Cavia porcellus: Phylum Chordata; Subphylum Vertebrata; Class Mammalia; Order Rodentia; Family Caviidae; Genus Cavia. The body is hairy. The jaws hold sharp incisor teeth. There are 4 clawed digits on each front foot and 3 on each hind foot. Two teats lie under the abdomen, and the outer ear has a pinna.

The fruit bat, Pteropus giganteus: Phylum Chordata; Subphylum Vertebrata; Class Mammalia; Order Chiroptera; Family Pteropodidae; Genus Pteropus. The body is hairy, with a pinna and mammary glands. The long forelimb digits are held up by a membrane, the patagium, which forms the wings. The bat is large and tailless, with a reddish-brown head and a black snout. The digits of the feet are curved and carry sharp claws. Guinea pig and bat are both Class Mammalia; only the Order differs.

3. Try it with your hands

The first viva question is usually the class. From the common name, drop each specimen into its class box.

Now the practical table. A vertebrate specimen comes up in the jar; look at its marks one by one and name it with as few as you can.

Now the other way round. From a mark, name the specimen. One or two unique marks are enough.

The classification line in an answer runs from largest to smallest, kingdom down to species. Tap the ranks in order.

4. Check yourself

Three questions in the exam's style.

The second asks you to name a specimen by its marks.

The last wants a tidy answer.

The whole note on six cards.

Source: Biology 2nd Paper (Zoology), Classes 11-12 (NCTB), Chapter 1 “Animal Diversity and Classification”, the “Practical: Identifying Vertebrate Specimens” part.