Ana səhifə

? Systematics or Taxonomy is the study of the kinds and diversity of organisms


Yüklə 45.21 Kb.
tarix27.06.2016
ölçüsü45.21 Kb.
ANIMAL CLASSIFICATION
? Systematics or Taxonomy is the study of the kinds and diversity of organisms.

? The modern classification is rooted in the work of Karl von Linne (Carolus Linnaeus).

? Modern taxonomists use five taxon or more as: Domain, Kingdom Phylum, Class, Order, Family, genus, and species.

? Many zoologists recognize three major groups within the animal kingdom: Mesozoa (Phylum Mesozoa), Parazoa (Phylum Porifera), and Eumetazoa (all other phyla).

? The Eumetazoa are further subdivided into: protestomes (Platyhelminthes, Nematoda, Mollusca, Annelida, and Arthropoda), and deuterostomes (Echinodermata, Hemichordata, Chordata, and others)

? Protozoa

? 1. Phylum Sarcomastigophora

consists of flagellates and amoeba within a single type of nucleus (with over 18,000 described species

Characteristics:

a) unicellular or colonial

b) locomotion by flagella, pseudopodia, or

both


c) autotrophic (self-nourishing), saprozoic

(living in decaying organic matter), or

heterotrophic (obtain energy from organic

compounds)

d) single type of nucleus

Euglena


• freshwater

• contains chloroplast with pyrenoid which

synthesizes and stores polysaccharide

• a pigment shield (stigma) permits light to

strike the photoreceptor from only one

direction

• haploid and reproduce by longitudinal binary

fission

Trypanosoma

Large and diverse, includes several species that infect

wild and domesticated animals in Africa, particularly

hoofed animals, and humans. Most of the African

trypanosomes are transmitted by vectors, and the most

common vector is the tsetse fly (Glossina sp.).

The species that cause human African trypanosomiasis

("sleeping sickness") also infect wild animals and can be

transmitted from these animals to humans

(zoonotic infections).

Most African trypanosomes are restricted to Africa,

although a few species have been imported into South

America.

Amoeba (Entamoeba histolytica)

• naked

• normally found in shallow water



engulf food by phagocytosis

• reproduce by binary fission

• particle feeders

• some are pathogenic line


Phylum Porifera - known as sponges; primarily marine

animals consisting of loosely arranged cells


• Assymmetrical or radially symmetrical

• Three cell types: pinacocytes, mesenchyme cells,

and choanocytes

• Central cavity, or a series of branching channels

• No tissue or organs
Class Calcarea – spicules composed of CaCO3; spicules are

needle-shaped and 3 or 4 rays; ascon, leucon or

sycon body forms; marine. Ex. Grantia

Class Hexactinellida

Spiculus composed of silica, usually six-rayed;

• spicules often fused into an intricate lattice;

• cup or vase-shaped; scycon or leucon body form;

• Glass sponges.

• Ex. Euplectella (Venus flower basket)

Class Demospongia

• Brilliantly covered sponges with needle-shapec or

• 4-rayed siliceous spicules or spongin or both;

• leucon body form;

• Ex. Spongilla, Cliona


Morphology:

• Pinacocytes line the outer surface of a sponge

• Pinacocyte may be mildly contractile, their combination

may change the shape of some sponges

• In some sponges, pinacocytes are specialized into

tubelike, contractile porocytes which regulate

water circulation

• Below the pinacocyte layer is a jelly-like mesohyl

composed of mesenchyme cells

• Mesohyl is specialized for reproduction, secreting skeletal

elements, transporting and storing food and forming

contractile rings around the openings in the sponge

wall.

• Below the mesohyl and lining the inner chamber is a layer



of collar cells or choanocytes which are flagellated

cells that have collarlike ring or microvilli surrounding

a flagellum. The flagellum creates water current

through a sponge and the collar filters microscopic food

particles from the water.

• Sponges are supported by a skeleton consisting of micro-

scopic needle like spikes called spicules. Made up of

calcium carbonate or silica, spicules are formed by

ameboid cells. Skelton is made up of spongin.
Body forms of a sponge

• 1) Ascon – vase-like; ostia are the outer opening of porocytes

and lead directly to a chamber called the spongocoel;

choanocytes line the spongocoel.

• 2) Sycon – the sponge walls appear folded; water enters

a sycon sponge through openings called dermal pores;

dermal pores are the openings of the incurrent canals

and connect to the radial canals; choanocytes line the

radial canals and the beating of choanocyte flagella

moves water from the ostia through incurrent and

radial canals, to the spongocoel and out the osculum.

• 3) Leucon – have an extensively branched canal system;

water enters the sponge through the ostia and moves

to the incurrent canals which lead to choanocyte-lined

chamber; the exit point of water is called oscula.
Reproduction

Most are monoecious (both sexes occur in the same

individual); asexual reproduction involves the

formation of gemmules (contain masses of ameboid

cells).
Phylum Cnidaria – hydra, anemone, jellyfish, coral

• Radial, or biradial symmetry

• Diploblastic tissue level organization

• Gelatinous mesoglea between the epidermal

and gastrodermal tissue layers

• Gastrovascular cavity

• Nervous system in the form of a nerve net

• Specialized cells called cnidocytes, used in

defense, feeding, and attachement
Class Hydrozoa – majority are marine; have colonial polyps

in which individuals may be specialized for feeding,

producing medusae by budding or defending the colony

Ex. Obelia, Hydra

Class Scyphozoa – “true jellyfish”, all are marine; often

deliver dangerous stings; Their primary food include

small plankton organisms such as mollusks, rotifers,

crustaceans, tunicate larvae, copepods, etc;

Ex. Aurelia aurita

Class Cubozoa – live in warm tropical waters; some possess

dangerous nematocyst.

Ex. Chironex flecken (sea wasp)


Class Anthozoa – marine, colonial, solitary, and lack medusae;

Ex. Sea anemone, corals. Corals are invertebrates that

are in symbiosis with an algae; they have an alternation

of generations during their life cycle (this cycle

alternates from a polyp to medusa stage). However, the

class anthozoa's medusa stage is absent because they

become sessile once they fix themselves in one place.

They only move during their developing stages.

To obtain food, corals filter feed, feeding on

invertebrates and fishes.

Phylum Ctenophora –sea walnuts or comb jellies; marine,

have a spherical form, although several groups

are flattened and/or elongate; bands of cilia called

comb rows are present for locomotion.

• Diploblastic tissue-level of organization

• Biradial symmetry

• Gelatinous mesoglea between the epidermal and

gastrodermal tissue layers

• Gastrovascular cavity

• Nervous system in the form of a nerve net


Class Tentaculata – with tentacles; Ex. Pleurobranchia

Class Nuda – without tentacles; Ex Beroe

Phylum Platyhelminthes – “flatworms”
• Usually flattened dorsoventrally, triploblastic, acoelomate,

bilaterally symmetrical, unsegmented worms

• Incomplete gut usually present; gut absent in Cestoidea

• Cephalization present, with an anterior cerebral ganglion

and usually longitudinal nerve cords

• Protonephridia as excretory/osmoregulatory structure

• Hermaphroditic, complex reroductive systems
Class Turbellaria – mostly free-living and aquatic; predaceous,

monoecious with reproductive systems adapted for

internal fertilization. Ex. Dugesia

Class Monogenea – monogenetic flukes; mostly ectoparasites

on vertebrates
Class Trematoda – all are parasitic; several holdfast devices

present; gut is present and most are monoecious

Ex. Paragonimus westermani

Class Cestoidea – are tapeworms and gut parasites of vertebrates;

structurally more specialized than the flukes, having

scolex and attachment organs, a neck region, and a

strobila which consists of a chain of segment; gut is

absent and the reproductive system is repeated in each

proglottid.

Phylum Nemertea – elongate flattened worms found in marine

and sand, are called “proboscis worms” because they

have long proboscis.


• Triploblastic, acoelomate, bilaterally symmetrical

unsegmented worm, possessing a ciliated epidermis

containing mucous gland

• Complete digestive tract and with an anus

• Protonephridia present

• Cerebral ganglion, longitudinal nerve cords, and

transverse commissures

• Closed circulatory system

• Body musculature organized into 2 or 3 layers

• Dioecious


Phylum Gastrotrichia – microscopic aquatic animals with a

head, neck, and trunk; numerous adhesive glands

are present; hermaphroditic; parthenogenesis is

common in freshwater species.
Phylum Rotifera – small animals, abundant in freshwater

habitats; ciliated “corona” in the anterior region of

the body; triploblastic, bilateral unsegmented,

complete digestive system; body covered by a cuticle

called “lorica”; feed on plankton organisms; reproduce

by parthenogenesis.

Phylum Kinorhyncha – minute worms living in marine habitats

bodies composed of 13 or 14 zomites, which have

cuticular scales, plates, spines. Ex. Echinoderes

Phylum Nematoda – roundworms, triploblastic, bilateral

vermiform; unsegmented, pseudocoelomate; complete

digestive tract; live in aquatic and terrestrial environments;

many are parasitic and of medicinal and agricultural

importance. Ex. Ascaris lumbricoides (intestinal round-

worm), Trichinella spiralis (porkworm)

Phylum Nematomorpha – elongate worms commonly called

horsehair worms or Gordian worms
Phylum Acantocephala – “spiny-headed worms” because of

their spiny proboscis; endoparasites in vertebrates


Phylum Loricifera – microscopic animals which have spiny head

and thorax; live in gravel and marine environments;

Ex. Nanaloricus mysticus
Phylum Priapulida – cucumber-shaped, wormlike animals;

live buried in the sand and mud in marine habitats;

Ex. Priapulus caudatus
Phylum Mollusca – soft-bodied animals
Body of 2 parts: head-foot and visceral mass

Mantle that secretes a calcareous shell and covers

the visceral mass

Mantle cavity functions in excretion, gas exchange,

elimination of digestive wastes, and release of

reproductive products

Protostome characteristics, including trochophore

larvae, spiral cleavage, and schizocoeleous coelom

formation

Coelom reduced to cavities surrounding the heart,

nephridia, and gonads

Open circulatory system in all but one class

(Cephalopoda)

Radula usually present and used in scraping food


Class Bivalvia – bivalves such as mussels and clams;

Ex. Mytilus


Class Gastropoda – Snails and coiled shells; Ex. Nerita
Class Cephalopoda – squids and octopus; foot modified

into a circle of tentacles and a siphon;

Ex. Octopus, Loligo, Nautilus

Phylum Annelida – segmented worms; triploblastic,

coelomate animals, shows metamerism, have complete

digestive tract


Class Polychaeta – “tubeworms”; predators, scavengers,

or filter-feeders; mostly marine and possess parapodia

with numerous setae. Ex. Nereis, Sabella

Class Oligochaeta – “earthworms”; includes primarily

freshwater and terrestrial annelids; possess few

setae, lack head and parapodia; scavengers;

Ex. Tubifex

Class Hirudinea – “leeches”; complex arrangement of

body-wall muscles, and the loss of septa influence

patterns of locomotion; predatory and feed on body

fluids, such as blood of vertebrates

Ex. Hirudo

Phylum Arthropoda – “jointed legs” animals
• Metamerism modified by the specialization of body

region for specific functions (tagmatization)

• Chitinous exoskeleton

• Paired, jointed appendages

• Growth is accompanied by ecdysis or molting

• Ventral nervous system

• Coelom reduced to cavities surrounding gonads and

excretory organs

• Open circulatory system

• Complete digestive tract

• Metamorphosis often present
Subphylum Trilobitomorpha

Subphylum Chelicerata

Class Arachnida – spiders, mites, ticks, scorpions
Subphylum Crustacea – mostly aquatic; head with 2 pairs of

antenna, I pair of mandible, 2 pairs of appendages;

biramous appendage

Class Branchiopoda – “water fleas”

Class Malacostraca – lobsters, crayfish, crabs, shrimps

Class Cirripedia – barnacles

Class Copepoda – copepods
Subphylum Uniramia

Class Hexapoda - with three pairs of legs; usually

two pairs of wings; with body, head, thorax and

abdomen; insects


Phylum Echinodermata – postradial symmetry; have an

endoskeleton of interlocking calcium carbonate and

ossicles; have a water vascular system that is used for

locomotion, food gathering, attachment, and exchanges

with the environment
Class Asteroidea – sea stars

Class Ophiuroidea – brittle stars and basket stars

Class Echinoidea – sea urchins, heart urchins, sand dollars

Class Holothuroidea – sea cucmbers


Phylum Hemichordata – live on marine sediments; includes

the acorn worms and the pterobranchs

Ex. Balanoglossus
Phylum Chordata – marine, freshwater and terrestrial habitats;

a notochord, pharyngeal slits, a dorsal tubular nerve

cord, and a post anal tail are all present at some time

in life histories


Subphylum Urochordata- sea quirts, tunicates

Subphylum Cephalochoradata – Amphioxus



Subphylum Vertebrata – lampreys, hagfishes, sharls,

bony fishes, frogs, reptiles, birds, mammals


Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©atelim.com 2016
rəhbərliyinə müraciət