Zoology Chart B. Sc- I

 

   Protochordata  (Acraniata)

                        Sub-phylum

           Urochordata                                                   Cephalochordata             

        (Eg. Herdmania,)                                                (Eg. Amphioxus)                            

Protochordate is commonly called lower chordates. These animals lack a head and a skull or cranium, so they are also known as Acraniata.  

On the property of notochord, Protochordates consist of three sub-phyla which are as follows.

1.  .   Urochordata

2. Cephalochordata.

These animals evolved from common ancestors.

2. Urochordata or Tunicata:

The notochord is only present in the tail of the larva ( hence named urochardata) and disappears in the adult.  The notochord occurs only in the tail of the larva and disappears in the adults called retrogressive metamorphosis

1.      They are marine,

2.      mostly sessile, filter–feeders.

3.      Body is enclosed in a leathery test or tunic sheath, composed of tunicin (cellulose) so-called tunicates.

4.      The nerve chord (neural tube) is present in the larva, but is replaced by a single dorsal ganglion in the adult.

5.      The gill slits or stigma are numerous, persist in adults, and open into the atrium, instead of opening to the exterior. There are no true gills but are called branchial baskets.

6.      Circulatory system is of open type. Blood consists of Venadocytes.

7.      Excretory system is lacking.

8.      Asexual reproduction occurs by budding.

                               

Examples: Herdmania, Salpa, Doliolum, etc.

 3. Cephalochordata:

1.       These are also marine and filter-feeders in feeding habits.

2.      The notochord extends up to the cephalic or head region and persists throughout life.

3.      The nerve chord persists throughout life, but no brain is formed.

4.      Excretion occurs by solenocytes.

5.      The gill slits are numerous and persist in adults.

6.      True gills are absent.

7.      The body wall consists of myotomes.

8.      Tail persists throughout life.

Hemichordates :

1.   All hemichordates are marine.
2. Some are solitary and slow-moving, and others are sedentary and colonial.
3. The body is stout and unsegmented, and has a worm-like or vase–like
4.   Three distinct regions namely proboscis, collar, and trunk are present.
5.   They are bilaterally symmetrical and triploblastic.
6.   Locomotory appendages are absent. The collar may bear arms and tentacles.
7. The body wall consists of a single-layered epidermis and a musculature of smooth longitudinal fibers.
8. Their body consists of a true coelom
9. The digestive tract is complete.
10. Feeding on microorganisms and are ciliary or filter feeders
11.   Proboscis contains a hollow-out growth from the gut, called the buccal diverticulum or stomochord and was regarded as a notochord in the past.
12. Respiration by pairs of gill slits or through the general body surface.
13. The circulatory system includes a dorsal heart, two main longitudinal vessels; a dorsal and a ventral, interconnected by small lateral vessels and sinuses.
14. Blood is colorless and without corpuscles.
15. The nervous system is diffuse consisting of an epidermal plexus of nerve cells and nerve fibers.
16. The excretory system comprises of a proboscis gland, or glomerulus,
17. Sexes are separate or hermaphrodites.
18. The gonads may be in several pairs or only one in pair.
19. Fertilization is external or internal.
20. Asexual reproduction may occur.
21. Development may include a free-swimming tornaria larva.

Examples:  Balanoglossus (the acorn worm), Cephalodiscus, Rhabdopeura etc.

                                          

Class – Pisces

1.  The presence of gills for respiration is an important characteristic of fishes.
2.  Their skin is covered with scales/plates. 
3. They lay eggs [oviporous].
4. Some fishes are ovi-viviparous.
5. Presence of paired and unpaired fins.
6.  fertilization is internal. 
7. presence of air bladder act as an organ of buoyancy in some fishes.  
8. They obtain oxygen dissolved in water by using gills.
9. The body is streamlined, and a muscular tail is used for movement.
10. They are cold-blooded and their hearts have only two chambers.
11. Some fish skeletons are made entirely of cartilage [Chondrichthyes], such as sharks, 
12.  some with a skeleton made of both bone and cartilage [Osteichthyes].

CLASS: Chondrycthys / Elasmobranch

GENERAL CHARACTERS

1. They are marine animals with streamlined bodies and have cartilaginous endoskeletons. 
2. The mouth is located ventrally.
3. The notochord is persistent throughout life.
4. Gill slits are separate and without operculum (gill cover).
5. The skin is tough, containing minute placoid scales.
6. Their jaws are very powerful.
7. These animals are predaceous [shark].
8. Due to the absence of air bladder, they have to swim constantly to avoid sinking.
9. Heart is two-chambered (one auricle and one ventricle).
10. Some of them have electric organs (e.g., Torpedo) and some possess poison sting (e.g., Trygon).
11. They are cold-blooded (poikilothermous) animals, i.e., they lack the capacity to regulate their body temperature.
12. Sexes are separate. In males pelvic fins bear claspers.
13. They have internal fertilization and many of them are viviparous [give birth to young ones].
14. Examples: Scoliodon (Dogfish), Pristis (Sawfish), Carchaiodon (Great white shark), and Trygon (Stingray).

Class- Osteichthyes

General Characters

1. It includes both marine and freshwater fishes with bony endoskeletons.
2. Their body is streamlined. 
3. The mouth is mostly terminal.
4. They have four pairs of gills which are covered by an operculum on each side.
5. Skin is covered with cycloid/ctenoid scales.
6. The air bladder is present in the teleost of bony fishes which regulates buoyancy.
7. The heart is two-chambered (one auricle and one ventricle).
8. They are cold-blooded
9. Sexes are separate.
10. Fertilization is usually external.
11. They are mostly oviparous and development is direct.
12. Examples: Flying fish, Sea horse, Fighting fish, Angel fish etc.

DOG FISH / Scoliodaon

Phylum  Chordata               Presence o f notochord, pharyngeal gill slits and dorsal tubular nerve cord.

sub-phylum     Vertebrata -     Notochord replaced by vertebral column or backbone,

Class - Chondrichthyes        Presence of the notochord, pharyngeal gill slits, and dorsal tubular nerve cord.

Superclass - Gnathostomata -    Mouth with true jaws paired appendages present in the form of fins

or limbs.

Order - Pleurotremata     -       pectoral fins moderate, constricted at the base.present behind the eye.

Includes sharks with 5-7 pairs of lateral gill slits, body

Genus -            Scoliodan

Species-           sorrakowah

  Character 

•         Scoliodon is commonly called as dogfish.

•         Body divisible into head, trunk and tail.

•         Presence of 5 pairs of gill slits.

•         Presence of paired and unpaired fins.

•         Tail is slightly bends upward.

In male pelvic fin shows presence of claspers

STING RAY

Sting ray (Trygon)

Phylum  chordata                    Presence o f notochord, pharyngeal gill slits and dorsal tubular nerve cord.

sub-phylum     Vertebrata -     Notochord replaced by vertebral column or backbone,

Class - Chondricthyes or                     Presence of notochord, pharyngeal gill slits paired appendages present in

Elasmobranchii                        the form of fins

Order   Hypotremata               body is flat dorso-ventrally presence of gill slits. Pectoral fin is fused to side

of body.

  Character        

•          Trygon is commonly called as sting ray.

•         Body is dorso-ventrally flattened.

•         Body consists of head trunk and long tail.

•         Five pairs of gills slits on ventral side of body.

•         Mouth is ventral in position.

•         Pectoral fins are much larger fused with body on lateral side.

•         Tail is long whip like with poisonous sting . 

ELECTIC RAY

Electric ray (Torpedo)

Phylum  chordata                    Presence o f notochord, pharyngeal gill slits and dorsal tubular nerve cord.

sub-phylum     Vertebrata -     Notochord replaced by vertebral column or backbone,

Class - Chondricthyes or         Presence of notochord, pharyngeal gill slits paired appendages present Elasmobranchii                          in the form of fins

Order   Hypotremata               body is flat dorso-ventrally presence of gill slits. Pectoral fin is fused

to side of body.

Comments.

•         The body of electric ray is dorso-ventrally flattened.

•         Body is divisible into body proper and tail.

•         Presence of large oval eyes located on mid-dorsal side of the head.

•         Pectoral fins are attached to the side of body laterally.

•         Mouth is transverse and situated ventrally.

•         Tail is thick and short with two dorsal fins and a caudal fin.

•         Viviparous animal

•         Mouth is present on ventral side.

•         Presence of electric organs which generate electric current used to kill preys or enimies.

LABEO :

Phylum -    Chordata         Presence o f notochord, pharyngeal gill slits and dorsal tubular nerve cord.

sub-phylum     Vertebrata -     Notochord replaced by vertebral column or backbone,

Class –            Ostechthyes    Endoskeleton is bony 4 pairs of gills slits.  gill slits paired                               appendages present in the form of fins.

Order-             Cyprinifores    Air bladder connected to pharynx.  Presence of Weberian

                                                ossicles between air bladder.

Genus – Labeo

Species – rohita      

Comment.

•         Labeo is commonly called as rohu.

•         Body is spindle shaped.

•         Body divisible into head, trunk and tail.

•         Body shows presence of paired and unpaired fins.

•         Presence of 4 Paris of gill slits.

•         Gills are covered with operculum.

•         Body is covered with cycloid scales .

 CHARACTERS

1.      It is commonly found in the fresh water ponds, lakes and river.

2.      Body is divisible in to head, trunk and tail.

3.      Labeo is commonly called as rohu.

4.      Body is spindle shaped.

5.      Body divisible into head, trunk and tail.

6.      Body shows presence of paired and unpaired fins

7.      Head is depressed. It bears mouth; paired nostrils and paired eyes.

8.      Two small threads like sensory maxillary barbells are present at the corners of the mouth. Mouth without teeth.

9.      Dorsal, anal, caudal, paired pectoral and anal fin with soft fin rays present. Caudal fin is homocercal i.e. having two equal lobes.

10.  Body covered with overlapping cycloid scales.

EXOCOETUS 

Phylum -       Chordata     Presence of the notochord, pharyngeal gill slits and dorsal                                                   tubular nerve cord.

sub-phylum     Vertebrata -    Notochord replaced by vertebral column or backbone,

Class –             Osteichthyes     Endoskeleton is bony 4 pairs of gills slits.  gill slits paired  

                                      appendages present in the form of fins.

ORDER        : BELONIFORMES

CHARACTERS

1.      Commonly known as flying fish.

2.      Silvery white body and is divisible in to bead, trunk and tail.

3.      Body covered with overlapping cycloid scales.

4.      Mouth small with teeth in both jaws.

5.      Dorsal and anal tins are short but pectoral fins are exceptionally large spread like wings and makes gliding flights. It can glide over the surface of the water for about 400 meters.

6.      Tail homocercal.

SEA HORSE

Phylum -        Chordata      Presence o f notochord, pharyngeal gill slits and dorsal tubular nerve cord. 
sub-phylum    Vertebrata -     Notochord replaced by vertebral column or backbone,
Class –          Ostechthyes    Endoskeleton is bony 4 pairs of gills slits.  gill slits paired                
                                              appendages present in the form of fins.
ORDER  : SYNGNATHIFORMES

CHARACTERS

1.      Commonly called as sea horse because its anterior end likes the head of a horse.

2.      Mouth terminal, toothless and suctorial.

3.      Body is divisible into head, trunk and tail.

4.      Single dorsal fin, ventral and caudal fins are absent.

5.      Tail is prehensile.

6.      It swims vertically with it majestic snout.

7.      Sexually dimorphic, males with a brood pouch on the belly for protecting eggs till hatching takes place

EEL FISH / ANGUILLA VULGARIS

Phylum -              Chordata         Presence o f notochord, pharyngeal gill slits and dorsal tubular nerve 

                                                    cord.

sub-phylum           Vertebrata -     Notochord replaced by vertebral column or backbone,

Class –           Osteichthyes    Endoskeleton is bony 4 pairs of gills slits.  gill slits paired                

                                                      appendages present in the form of fins.

O

 Order - Amguliforme

 CHARACTERS

1.      Commonly known as eel fish. It is fresh water fish and can live several hours outside the water.

2.      Body is slender elongated and snake like. It is divisible into head, trunk and tail.

3.      Head contains a mouth, eyes, and nostrils. On each side, the operculum covers the gill slits.

4.      Dorsal fin, anal fin and caudal fin are joined together forming a continuous fin. Small pectoral fins behind the operculum.

5.      They have a peculiar breeding habit. 

CLASS : AMPHIBIA

GENERAL CHARACTERS

1.  These are cold-blooded vertebrates.
2.  Skin is smooth or rough, rich in glands
3. Skin is with large numbers of mucus glands
4.  Limbs with webbed digits
5.  Red blood cells are biconvex, oval, and nucleated.
6. Three-chambered heart, with two auricles, and one ventricle.
7.  gills are present in tadpole stage  
8.  Eggs with gelatinous covering, usually laid in water.
9.  The larva passes through the aquatic stage before metamorphosing into an adult.

ICHTHYOPHIS

Phylum –Chordata (Notochord is present, Dorsal tubular nerve   cord.)
Sub-phylum – Vertebrata (Vertebral column is present)
Class – Amphibia (cold-blooded, aquatic and terrestrial, skin moist)
Order – Apoda (Burrowing vermiform, without limbs& girdles.)
Genus – Ichthyophis
Species - glutinosa

CHARACTERS

 1. Ichthyophis is a burrowing elongated & eel-type animal.

2. Ichthyophis is a burrowing elongated & eel type of animal.

2. It measures up to 30 cm in length.

3. The colour of body is dark brown or bluish-black with a yellow band along the side.

4. Fertilization is external.

5. Completely aquatic.

.FROG

•      Phylum –Chordata (Notochord is present, Dorsal tubular nerve   cord.)

•      Sub-phylum – Vertebrata (Vertebral column is present)

•      Class – Amphibia ( cold blooded, aquatic and terrestrial, skin moist)

•      Order – Anura (Tail less animal)

•      Genus – Rana

•      Species – tigrina       

   Characters –

1.It is commonly called as bull frog

2. Body is green with black patches

 3. Head is flat & more or less triangular

 4. eyes are large with eyelid &      nictating membrane.

5. A pair of tympanum lie behind eyes

6. Carnivorous, feeding small worms, snails, aquatic insects.           

TOAD

Phylum –Chordata (Notochord is present, Dorsal tubular nerve   cord.)
Sub-phylum – Vertebrata (Vertebral column is present)
Class – Amphibia ( cold blooded, aquatic and terrestrial, skin is moist)
Order – Anura (Tail less animal)
Genus – Bufo     
Species – melanosticus

CHARACTERS

1. It is commonly called as a true- toad.

2. Skin is rough, dry, and watery on the dorsal surface of the body.

3. Eyes are large & nostrils are very small.

4. Tympanum is very well developed.

5. Paired parotid glands are present behind the tympanum, 

These secrete a poisonous fluid that is irritating.

6. Fore limb bears three webless fingers & a thumb pad.

7. Hind limb has three toes with a greatly reduced web.

SALAMANDER

Phylum –Chordata (Notochord is present, Dorsal tubular nerve   cord.)
Sub-phylum – Vertebrata (Vertebral column is present)
Class – Amphibia ( cold blooded, aquatic and terrestrial, skin moist)
Order – Apoda (Burrowing vermiform, without limbs& girdles.)
Genus – Ichthyophis
Species - glutinosa

CHARACTERS:

1. Salamandra is commonly known as European fire salamander & terrestrial in habit.

2. Body is lizard-like in appearance. The colour is black with yellow spots.

3. Limbs are well-developed & strong. 

The tail is cylindrical.

4. Eyelids are movable. The tympanic membrane or middle ear is absent.

5. Teeth are present on both jaws.

6. Young ones born having the external gills & metamorphosis takes place later.