Animal Kingdom 1 Flashcards
how do we identify animals
- cellular structure( cellwall)
-eukaryotic - heterotrophic
what are the different levels of organisation” cellular
Though all members of Animalia are multicellular, all of them do not
exhibit the same pattern of organisation of cells. For example, in sponges,
the cells are arranged as loose cell aggregates, i.e., they exhibit cellular
level of organisation. Some division of labour (activities) occur among
the cells.
what is tissue level of organisation
In coelenterates, the arrangement of cells is more complex. Here
the cells performing the same function are arranged into tissues, hence is
called tissue level of organisation.
what is the organ level of organisation
A still higher level of organisation, i.e.,
organ level is exhibited by members of Platyhelminthes and other higher
phyla where tissues are grouped together to form organs, each specialised
for a particular function.
wha is organ system level of organisation
In animals like Annelids, Arthropods, Molluscs, Echinoderms and Chordates, organs have
associated to form functional systems, each
system concerned with a specific physiological
function. This pattern is called organ system
level of organisation. Organ systems in different
groups of animals exhibit various patterns of
complexities.
give two examples of complete and incomplete organ systems
For example, the digestive system
in Platyhelminthes has only a single opening
to the outside of the body that serves as both
mouth and anus, and is hence called
incomplete. A complete digestive system has
two openings, mouth and anus.
Similarly, the
circulatory system may be of two types:
(i) open type in which the blood is pumped
out of the heart and the cells and tissues are
directly bathed in it and
(ii) closed type in which the blood is circulated
through a series of vessels of varying diameters
(arteries, veins and capillaries).
what are assymetrical organisms
Animals can be categorised on the basis of their
symmetry. Sponges are mostly asymmetrical,
i.e., any plane that passes through the centre
does not divide them into equal halves.
what are two types of symmetry
When
any plane passing through the central axis of
the body divides the organism into two identical
halves, it is called radial symmetry.
Coelenterates, ctenophores and echinoderms
have this kind of body plan (Figure 4.1a).
Animals like annelids, arthropods, etc., where
the body can be divided into identical left and
right halves in only one plane, exhibit bilateral
symmetry
what are no of germinal layers
no of layers present in embryo
they are classified into diploblastic and triploblastic
what are diploblastic animals
Animals in which the cells are arranged in two
embryonic layers, an external ectoderm and
an internal endoderm, are called diploblastic
animals, e.g., coelenterates. An undifferentiated
layer, mesoglea, is present in between the
ectoderm and the endoderm. Mesoglea is a jelli-like substance.
what are triploblastic animals
Those animals in which the developing embryo has a third germinal layer,
mesoderm, in between the ectoderm and endoderm, are called
triploblastic animals (platyhelminthes to chordates, Figure 4.2b).
what is a coelom
Coelom is the body cavity present between the body wall and the gut wall, lined by the mesoderm.
Animals
possessing coelom are called coelomates, e.g.,
annelids, molluscs, arthropods, echinoderms,
hemichordates and chordates
what are pseudocoelomates and acoelomates
4.3a). In
some animals, the body cavity is not lined by
mesoderm, instead, the mesoderm is present as
scattered pouches in between the ectoderm and
endoderm. Such a body cavity is called
pseudocoelom and the animals possessing them
are called pseudocoelomates, e.g.,
aschelminthes (Figure 4.3b). The animals in
which the body cavity is absent are called
acoelomates, e.g., platyhelminthes (Figure 4.3c).
what is segmentation
In some animals, the body is externally and internally divided into
segments with a serial repetition of at least some organs.
Each segment is called metamere
This pattern is called metameric segmentation and the phenomenon called metamerism
what is notochord
Notochord is a mesodermally derived rod-like structure formed on the
dorsal side during embryonic development in some animals. Animals with
notochord are called chordates and those animals which do not form this
structure are called non-chordates, e.g., porifera to echinoderms.
Notochord forms the vertebral columns
