Animal kingdom classification with different phyla
Answers
Answer:
Explanation:
Classification of kingdom Animalia:
Kingdom Animalia is subdivided into several phyla, starting with the simplest development and going up:
Porifera: sponges
Cnidaria : small asexual animals like hydra
Ctenophora: marine ciliated animals
Platyhelminthes : flatworms like tapeworm
Nemathelminthes: cylindrical unsegmented worms, like roundworms
Annelida : segmented worms like earthworm
Arthropoda :possesses jointed appendages; all spiders, crustaceans, insects, etc.
Mollusca: calcareous exoskeleton; snails, mussels, octopuses, squids, cuttlefish, etc. (Some are without exoskeleton like slugs, and some have endoskeleton like cuttlefish).
Echinodermata: starfish, sea urchins, etc.
Chordata: All animals in which an embryonic or persistent notochord is present.
Upto phylum Nemathelminthes, all animals are diploblastic. That means their bodies have essentially two layers during formation. Annelida and upwards to chordates are triploblastic, their bodies have three layers. Triploblastic animals also have coelom, although the lower forms may not, or may have pseudocoelom.
As for symmetry, simpler animals have radial symmetry and more complex ones have bilateral symmetry, although a good exception is Echinodermata; echinoderms are radial, but their development is much advanced, and some larval forms are similar to Hemichordate larval forms.
Phylum Chordata is divided into four subphyla
Hemichordata: these are worm like aquatic creatures with a notochord. An example is Balanoglossus. Modern taxonomy often records Hemichordata as a separate phylum and not part of Chordata at all. In that case, phylum Chordata will have only three subphyla.
Urochordata: these are sessile creatures like sea squirts, although the larval forms are free living.
Cephalochordata: they are marine free living forms which possess all Chordate characters in adult or larval life.
Vertebrata: All animals with a vertebral column enclosing the central nerve cord.
Vertebrata is further subdivided into five classes:
Pisces: completely aquatic. All vertebrate fishes, either bony or cartilaginous. Two chambered hearts. Mostly oviparous (lays eggs).
Amphibia: lives both on land and water. Frogs, cryptobrancs. Three chambered hearts. Oviparous.
Reptilia: mostly live on land. Some are water dwellers but many of these come to the surface to breathe air. All turtles, lizards, crocodiles, snakes. Three chambered hearts with incompletely divided ventricle. Oviparous.
Aves: Birds. Four chambered hearts. Oviparous.
Mammalia: All mammals and marsupials. Mostly four legged, body hair present. Produces milk for young. Includes primates such as monkey and human. Four chambered hearts. Viviparous (live births). All are placentates except marsupials.
It must be noted that all the phyla from Porifera to Echinodermata are also similarly divisible into multiple subphyla, classes and subclasses, etc. In academic interest, usually vertebrata is explained as a relatable example.
Also, all animals can be further classified into protostomia and deuterostomia. Protostomes are all which develop their mouths from the blastopore and deuterostomes develop a second pore that grows into mouth and blastopore gives rise to anus. All phyla from Echinodermata to Chordates are deuterostomes and all others are protostomes.
Note: till recently, Protozoa was considered a phylum of Animalia but now has its own kingdom, Protista, which includes all single celled eukaryotic organisms.