Selaginella: features, morphology ,anatomy and reproduction.
Classification of animals
1.
2. Classification
of animals
"The arrangement of
entities in a hierarchical
series of nested classes,
in which similar or
related classes at one
hierarchical level are
combined
comprehensively into
more inclusive classes
at the next higher
level." A class is defined
as "a collection of
similar entities"
3.
4. COELENTERATA/
CNIDARIANS
All coelenterates are aquatic,
mostly marine. The
bodyform is radially
symmetrical with a tissue
grade of organisation. The
body has a single opening
hypostome surrounded by
sensory tentacles leading
into a spacious cavity called
the gastrovascular cavity or
coelenteron. Digestion is
both intracellular and
extracellular. Respiration
and excretion are
accomplished by simple
diffusion. A network of
nerves is spread throughout
the body.
5.
6. Coelenterata is an obsolete term encompassing two animal phyla, the
Ctenophora (comb jellies) and the Cnidaria (coral animals, true jellies, sea
anemones, sea pens, and their allies). The name comes from the Greek "koilos"
("full bellied"), referring to the hollow body cavity common to these two phyla.
They have very simple tissue organization, with only two layers of cells,
external and internal and radial symmetry. Some of the examples are corals,
sea anemone which are colonial and hydra, jelly fish which are solitary.
History of classification
The term coelenterate is no longer recognized as scientifically valid, as the
Cnidaria and Ctenophora have less in common than previously assumed.[1] Any
group containing the two but excluding other phyla would be paraphyletic.
Nonetheless, the term coelenterate is still used in informal settings to refer to
the Cnidaria and Ctenophora.
Complicating the issue is the 1997 work of Lynn Margulis (revising an earlier
model by Thomas Cavalier-Smith) that placed the Cnidaria and Ctenophora
alone in the branch Radiata within Eumetazoa.[2] (The latter refers to all the
animals except the sponges, Trichoplax, and the still poorly understood
Mesozoa.) Neither grouping is accepted universally;[3] however, both are
commonly encountered in taxonomic literature.
The Coelenterata hypothesis has been more recently revived, based on
molecular data, placing the Coelenterates as a monophyletic sister-group to the
Bilateria
7. MOLLUSCA
The molluscs or
mollusks compose the
large phylum of
invertebrate animals
known as the
Mollusca. Around
85,000 extant species
of molluscs are
recognized. Molluscs
are the largest marine
phylum, comprising
about 23% of all the
named marine
organisms.
8.
9. Gastropods, the group of mollusks that include the terrestrial snails and
slugs and the marine limpets, periwinkles, abalones, whelks, and their
relatives, are the largest and most varied class of mollusks, with more than
75,000 extant species in addition to 15,000 fossil forms that are known.
These successful animals are the only class of mollusks to occupy both
marine, fresh-water, and terrestrial environments. In the sea, most species
are epibenthic, crawling on the surface, but there are some swimming forms
as well (some types of Opisthobranchia). Although many gastropods are
herbivorous grazers, several groups are active carnivores able to drill
through the shell of their victim, or in the case of predatory forms like the
Conidae (Neogastropoda) cases swallow it whole through a proboscis.
Most of the gastropods are classified on the characteristics the gill
structures and other soft-bodied features. Few distinguishing characters of
the shell are used in classification as many are the result of convergent
evolution. Although the differences in the shell form may be difficult to
recognize, different morphologic groups can generally can be differentiated
on characteristics of ornamentation, shell shape, and aperture. The shell of
many gastropods can either be external or, less commonly, internal. The
difference can often be deduced by the luster of shell material and the
presence of other features such as deviations of a structural shell form.
19. a.Marsupials
Commonly known as
marsupials, members
are divided into seven
orders;
Didelphimorphia,
Paucituberculata,
Microbiotheria,
Dasyuromorphia,
Peramelemorphia,
Notoryctemorphia, and
Diprotodontia. the
members of the order
Marsupialia are pouch-
bearing mammals who
give birth to
underdeveloped
offspring( Koalas,
Possums, Kangaroo,
Wallabies )
20.
21. b.Primates
The mammalian order
Primates contains over
230 species and includes
the prosimians, monkeys
and apes. All primates
are omnivorous,
although many who live
in rain forests eat
vegetation almost
exclusively. Primate eyes
face forward which
allows for binocular
vision ( Prosimians,
Monkeys, Apes and
Humans )
22.
23. c.Rodents
he order Rodentia consist
of nearly 2000 species or
mice, rats, squirrels,
gophers, porcupines and
various other rodents,
and is the largest
mammalian order. The
worlds largest rodent is
the capybara while the
smallest is the pygmy
mouse. Rodents naturally
occur everywhere around
the world with the
exception of Antarctica
and New Zealand, but
have been introduced
there as well. ( Rodents )
24.
25. Marine
mammal
Marine mammals, which
include seals, whales, dolphins,
otters and walruses, form a
diverse group of 129 species that
rely on the ocean for their
existence.[1] They do not represent
a distinct biological grouping, but
rather are unified by their reliance
on the marine environment for
feeding.[2] The level of
dependence on the marine
environment for existence varies
considerably with species. For
example, dolphins and whales are
completely dependent on the
marine environment for all stages
of their life, whereas seals feed in
the ocean
26.
27. Flying
Mammals
The bats are the representative
animal of this group.
Bats have many unusual
characteristics. They cannot walk
very well because skin that
reaches over its front and back
legs. It flies at night and stays in
caves and other dark places
during the day., Hanging upside
down by the claws of its back legs.
They look like flying mice.
Bats eat insects, although the
vampire bat drinks blood. Bats fly
in total darkness and have keen
hearing. They listen for sounds
and echoes to guide their flight.
Bats can be helpful in eating
insects but can be harmful as they
can carry such germs as rabies.
