basis 0f classification Flashcards
what are the 7 features used as the basis of animal classification?
1) levels of the organisation
2) body symmetry
3) coelomic cavity
4) germ layer
5) pattern of digesting and respiratory system
6) segmentation
7) notochord
explain the different levels of organisation in kingdom Animalia?
1) cellular level:
- cell is the basic unit and performs all the vital function
- cells are arranged loosely in a cell aggregate without forming a tissue
- there is some division of labour among the cells
- found in Porifera
- cell aggregate is a cluster of cells with little labour division usually present in sponges
2) tissue level:
- groups of tissue constitute the body
- present in coelenterates/cnidaria and ctenophores
3) organ level :
- tissues come together to form organs
- Platyhelminthes
4) organ system level:
- organs form organ systems
-aschelminthes to Chordata
explain the different body symmetries in kingdom Animalia?
biradial symmetry is when the body is divisible from one or two verticle plains. present in sea anemones
- the phenomenon of splitting the body into equal halves
1) asymmetry: - the body lacks symmetry
- most poriferens except Leucosolenia
2) radial symmetry:
- number of similar parts radiating from the central axis.
- body is divisible into equal plane y cutting from any plane
- Coelenterata, ctenophores, adult Echinodermata
- permits animals to find food or danger from any side
- mostly cylindrical shape with oral(mouth)surface and aboral surface.
3) bilateral symmetry:
- body is divisible into equal halves in one single plain.
- because the important body organs are paired and occur on the two sides of a central axis.
- Platyhelminthes to Mollusca larva of echinoderm, chordates
- Bilateral symmetry constitutes the second major evolutionary advance in the animal body plan.
- bilateral symmetry arose when animals on the ocean floor became mobile, this lead to cephalization
- spherical in shape and indistinguishable from any side
- can be divided into equal halves by any plane passing through the centre
- eg: volvox, colonial green algae
explain the different germ layers in the kingdom Animalia?
undifferentiated jelly-like layer called mesoglea layer present between ectoderm and endoderm in diploblastic organisms. they are not specialized to form any tissue
zygote –> morula –> blastocysts –>ectoderm, endoderm, mesoderm
diploblastic organism = developing embryo has only Ectoderm and endoderm
eg: porifera & cnidaria.
triploblastic = developing embryo has endoderm, ectoderm and mesoderm
E.g., platyhelminthes to chordates.
explain the different coeloms in the kingdom Animalia?
- body cavity present between the body wall and gut wall lined by mesoderm
1) acoelomate : - lacks true coelom or body cavity
- Porifera ,Coelenterata . ctenophores and Platyhelminthes.
- means without body cavity which is due to failure of mesoderm to cavitate during embryogeny
- parenchyma fils the body cavity of Platyhelminthes.
2) pseudocoelomates:
- mesodermal coelomic pouches are present but are incomplete.
- body cavity is not completely lined by mesoderm.
- - aschelminthes
3) eucoelomate:
- completely well-developed coelom, which arises as a cavity in embryonic mesoderm.
- mesoderm provides cellular lining to the cavity. called epithelium or peritoneum.
- peritoneum secrets coelomic fluid and fills the coelomic cavity.
- In arthropoda and molluscs, the actual or true coelom is reduced but spaces between viscera, grow and form a large cavity filled with blood called haemocoelom.
- reults in tube within line design
a) shizocoelomate:developed by splitting up of mesoderm
- found in arthopod molluscs and annelids
b) enterocoelm: mesoderm arises from the embyonic gut wall or enteron as enterocoelomnic pouches or hollow outgrowth.
- found in echinodermes and chordates.
what are sessile?
organisms with radial symmetry that are attached to a solid support (substratum)by the aboral surface and are called sessile.
what is cephalization?
the mouth of crawling animals is developed at the end that goes ahead. with the mouth, all the sensory organs and a brain are developed at the frontal end, thus the head with the brain became associated with the mouth end. this is called cephalization.
begins in Platyhelminthes.
explain the different body plans present in the Animalia kingdom?
1) cell aggregate: composed of clusters or aggregation of cells that are not organized into tissues or organs.
2) blind sac: single opening acting as mouth and anus.
- cnidarians, poriferan, Ctenophora, Platyhelminthes
3) tube within a tube: mouth and anus are separate openings.
- digestive system is a digestive canal with two openings at each end, i.e mouth and anus.
a) protostomes:
- first opening is the mouth which is developed in the embryonic digestive tube. the blastopore forms the mouth. the second opening is the anus.
- annelids, mollusc and arthropods lines.
b) deuterostomes:
- blastopore forms the anus
- anus is developed the first mouth is developed later.
- chordates and echinoderms
explain the pattern of complexity in the digestive system?
1) incomplete
- single opening for ingestion and digestion
- hydra, Ctenophora and most Platyhelminthes
2) complete
- two openings for the anus and mouth
- aschelminthes to chordates
explain the pattern of complexity in the respiratory system?
1) aerobic
- requires oxygen for respiration
2) anerobic
- does not requires oxygen for respiration
explain the pattern of complexity in the reproductive system?
1) asexual along withg sexual: ceolentrates , sponges
2) sexual reproduction is predomenant in highe animals
explain the pattern of complexity in the circulatory system?
1) open
- tissue and cells are bathed in blood
- direct contact and exchange between cells and blood pumped by the heart
- arthropods , hemichordates , non-cephalopod mollusk and tunicates
2) closed
- blood travels through vessel of varying diameter and maintains continuous bl0ood flow
- no erect contact between blood and cells
- exchange occur through capillaries
- annelids ,cephalopod mollusk, chordates
explain the classification of animals based on body temprature?
1)warm blooded(OR HOMEOTHERMIC ANIMALS)
-Also known as endotherms.
- relatively constant body temperature temperature is –body independent of that of their external environment.
-Body temperature is derived from heat produced by their own oxidative metabolism and the presence of insulating hair, features and blubbers prevents this internally generated heat from freely diffusing to the external environment.
E.g., Mammals and birds.
2) cold blooded(OR HOMEOTHERMIC ANIMALS)
- Also known as ectotherms.
- Their body temperature varies. These do not keep their body temperature constant so when their body temperature is high (on a hot summer day), these can be very active and when it is low (on a cold winter’s night) and can produce energy only slowly.
E.g., invertebrates, fish, amphibians and reptiles. These defend in two ways- hibernation and aestivation.
explain segmentation?
1)true segmentation
-body divided into complete segments
eg:arthopoda
a)Mesmerism : type of segmentation
-body structure that is n a linear series and is fundamentally similar . It helps develop specialization of organs.
E.g., annelids.
Mesmerism results in the separation of mesoderm into segmented blocks of muscles.
2) False segmentation or pseudometamerism
- through budding in tapeworm.
- the body is divided into many segments known as proglottids.
- Arthropods shows only external segmentation.
- In chordates, only internal segmentation is present
- segmentation abestnt in mollusk and echinoderms
explain notochord?
notochord is elongated flexible structure formed in some animals.
- derived from mesoderm
- formed on the upper or dorsal side of embryo and defines its primitive axis
- acts as internal skeleton or endoskeleton and supports the body
- all chordates have a notochord
- non-chordates don’t have a notochord, they have a double ventral nerve chord. porifera to hemichordates
- chordates have both notochord and ventral nerve chord
- notochord replaced by a vertebral column in vertebrate
- hemichordates have stomochordes, which is a flexible hollow tube