Observation and Classification of Specimens

EXERCISE 6 ARTHROPODA: OBSERVATION AND CLASSIFICATION OF SPECIMENS

Structure

6.1 Introduction Objectives 6.2 Materials Required 6.3 General Characters and Classification of Arthropoda 6.4 Subphylum Chelicerata General Characters Class Arachnida Class Merostomata 6.5 Subphylum Crustacea General Characters Class Malacostraca 6.6 Subphylum Uniramia General Characters Class Chilopoda Class Pauropoda Class Insecta 6.7 Terminal Questions

6.1 INTRODUCTION

Before you go through this exercise you are advised to refer to Unit 8, Block 2, of the Animal Diversity course and try to recapitulate the salient features and characters of Phylum Arthropoda and its classification.

In this exercise you will examine and identify some of the common representatives of Arthropoda. The phylum Arthropoda as the name signifies (arthros = joined + podos = foot) are the animals which possess jointed appendages. Arthropoda constitutes the largest phylum of animal kingdom comprising animals like crabs, lobsters, scorpions, spiders, millipedes, centipedes and insects such as cockroaches, bedbugs, houseflies, mosquitoes, butterflies and honeybees. In this exercise you will study the specimens of Palamnaeus, Limulus, Palaemon, Cancer, Scolopendra, Julus, Periplaneta, and Apis. Objectives

After performing this exercise you should be able to:

• identify Palamnaeus (scorpion), Limulus (king crab), Penaeus/Palaemon (prawn), Scolopendra (centipede ) , Julus (Millipede ), Periplaneta (cockroach) and Apis (honeybee) and give their scientific and common names,

Animal Diversity: • classify the identified arthropods up to the level of the class Laboratory • list characters justifying their classification and mention special features, if any,

• mention the habit, habitat and geographical location of the identified genera,

• draw labelled diagrams of the identified specimens and

• mention economic importance, if any, of each of the identified genera. 6.2 MATERIALS REQUIRED

1. Preserved specimens/permanent slides of the following animals:

Palamnaeus (Scorpion)

Limulus (King crab)

Cancer (Crab)

Scolopendra (Centipede)

Julus (Millipeda)

Palaemon (Prawn)

Periplaneta (Cockroach)

Apis (Honey bee)

2. Compound Microscope

3. Hand Lens

4. Magnifying glass

5. Practical Record Book

6. Pencil

7. Rubber 6.3 GENERAL CHARACTERS AND CLASSIFICATION OF ARTHROPODA

These are metamerically segmented animals with an exoskeleton of cuticle. Schizocoelic coelom is much reduced and is replaced by perivisceral haemocoel, which is filled with blood. Circulatory system is of open type. True nephridia are absent, but coelomoducts act as gonoducts and often as excretory organs. Body of the animal is bilaterally symmetrical. They also bear paired appendages. You will examine, identify and draw labelled line diagrams of the preserved specimens/ permanent slides of the whole mounts of the animals. You are supposed to write the comments on the observations you have made.

Arthropoda: 6.4 SUBPHYLUM CHELICERATA Observation and Classification of 6.4.1 General Characters Specimens The subphylum Chelicerata includes familiar horse shoe crab, spiders, scorpions, ticks and mites. i) Body consists of an anterior prosoma and a posterior opisthosoma. ii) Prosoma bears the appendages involved in feeding and locomotion. Opisthosoma may have exterior segmentation but appendages are either absent or considerably reduced. iii) Their main appendages are chelicerae and pedipalpi. iv) Antennae and mandibles are absent. v) These are the first land animals in evolution of arthropoda which have successfully colonised the terrestrial environment. 6.4.2 Class – Arachnida

The class Arachnida ( arachne = spider) has terrestrial and few aquatic animals. It includes spider, scorpions and mites. i) Prosoma bears six pair of appendages: one pair of chelicerae, one pair of pedipalpi and four pairs of walking legs. ii) Abdomen is generally devoid of appendages. iii) Respiratory organs are tracheae, book lungs and book gills. iv) Excretion is performed by malpighian tubules and coxal glands. v) Sexes are separate but sexual dimorphism is not conspicuous.

So, you have refreshed your background knowledge of the characters of subphylum Chelicerata and class Arachnida. Let us now study individual examples under the class Arachnida.

Example – Palamnaeus (Scorpion)

Examine the specimen both from dorsal and ventral sides. Observe the following features: i) It has dark coloured body to match with the surroundings. The underside is pale yellow. ii) Body is divided into prosoma or cephalothorax and opisthosoma or abdomen. Prosoma is covered by square shaped shield of dorsal carapace. iii) Dorsal carapace has right and left frontal lobes. It also bears a pair of median eyes with 213 pairs of smaller lateral eyes on the antero lateral margins. Eyes are simple in structure. On the ventral surface of the prosoma there is a single, median, small, triangular plate, the sternum . It lies between the coxa of the 3 rd and 4 th pair of legs. iv) Opisthosoma is distinguished as anterior mesosoma and posterior metasoma. Mesosoma consists of seven segments. Each segment is 69

Animal Diversity: covered by tergal plates dorsally and sternal plates ventrally. Both are Laboratory joined laterally by pleural membrane.

v) Sternum of the first mesosoma bears genital aperture which is covered by a genital operculum. Sternum of second segment bears comblike appendages called pectines. Pectine has small comblike 2426 bristles.

vi) Metasoma or postabdomen is slender and consists of five cylindrical segments with a telson or sting . The sting comprises an ampulla and a distal spine or aculeus. Ampulla contains poison glands with an opening at the tip of the distal spine.

(a) (b) Fig. 6.1: Palamnaeus , A -Dorsal view; B – Ventral view.

vii) Scorpion has six pairs of appendages. These are a pair of chelicerae , a pair of pedipalp and four pairs of walking legs . Chelicerae are threesegmented with two distal segments forming chela. Pedipalps have six joints, walking legs are composed of coxa, trochanter, femur, tibia and three tarsi.

viii) Respiratory system is highly characteristic consisting of 4 pairs of book lungs or pulmonary sacs. Paired book lungs are situated on the ventro lateral sides of the 3 rd , 4 th , 5 th and 6 th mesosomal or preabdominal segments.

ix) Sexes are separate.

Habit and Habitat

Scorpion is nocturnal found under stones or bark of trees or in burrows.

Geographical Distribution: Most tropical and subtropical countries. Very common in India, most prevalent in Maharashtra, Assam, Rajasthan, Saurashtra and Uttar Pradesh.

Classification and its Justification

Kingdom Animalia Animals, multicellular organisms with cells

that lack a cell wall, many capable of Arthropoda: Observation and movement or movement of some of their body Classification of parts or capable of movement at some time of Specimens their life cycle; heterotrophic nutrition.

Phylum Arthropoda Jointed appendages, segmented body.

Subphylum Chelicerata Main appendages are chelicerae and pedipalpi, body divided into prosoma and opisthosoma.

Class Arachnida Four pairs of walking legs

Genus Palamnaeus

Species bengalensis

Common Scorpion Name 6.4.3 Class Merostomata

The Class Merostomata are aquatic chelicerates in which five or six pairs of abdominal appendages are modified into gills. At the end of body there is a sword like telson.

Example Limulus (king crab)

King crab (also called horse shoe crab) is not really a crab, true crabs are included in Malacostraca. King crab is the largest living merostome. It comes under the category of living fossils.

Examine the specimen from both dorsal and ventral sides and look for the following features: i) Limulus is horseshoe shaped crab with dorsally convex carapace covering prosoma. The posterior side of the body is fitted into the slots of carapace. ii) A long caudal spine extends from the rear of the opisthosoma. Spine helps in locomotion. It is neither offensive nor defensive in function. iii) Ventral side bears segmental appendages. Flanking labrum are chelicerae. Three segmented chelicerae form the pincers, forming a chelate appendage. iv) Opisthosoma is hexagonal broadly joined to prosoma and consists of mesosomatic segments, an unsegmented vestigial metasoma. v) The next four pairs are chelated legs and the 6 th pair is nonchelate legs. Just behind the mouth an oral platelike appendage called chilaria is present. vi) The mesosomatic appendages are flattened and platelike. The first pair is united in the middle to form a genital operculum. Exopodite of the remaining five pairs bears respiratory book gills.

Animal Diversity: Laboratory

(a) (b)

Fig. 6.2: Limulus . A) Dorsal view; B) Ventral view.

vii) Horse shoe crab eats polychaetes, small molluscs and soft invertebrates of the ocean floor.

viii) The foregut of Limulus includes an oesophagus and a gizzard, the midgut comprises a stomach and paired hepatic caecae and an intestine.

Habit and Habitat

Marine animal found in shallow waters, burrowing in sand, sluggish and mostly buried in sand. Feeds on soft mollusca and other small animals.

Geographical Distribution: North Western Atlantic coast, Gulf of Mexico, West Indies, also South East Asian Pacific coasts.

Classification and its Justification

Phylum Arthropoda Jointed appendages, segmented body.

Subphylum Chelicerata Main appendages are chelicerae and pedipalpi, body divided into prosoma and opisthosoma.

Class Merostomata Five or six abdominal appendages modified into gills.

Subclass Xiphosura Swordlike telson at the end of the body.

Genus Limulus

Common King crab or Name horse shoe crab

Arthropoda: 6.5 SUBPHYLUM CRUSTACEA Observation and Classification of 6.5.1 General Characters Specimens Body of crustaceans is covered externally by chitinous cuticle and bilaterally symmetrical, triploblastic and is divisible into three regions head, thorax and abdomen.

Crustaceans are mainly aquatic arthropods with gills for respiration but a few live in moist places. These possess telson and variable number of metameres. A cephalothorax is present in most of the crustacea, formed by the fusion of the head and thoracic metameres into a uniform tagma. Cephalothorax has usually a carapace. Head bears a pair of compound eyes and five pairs of appendages. Thorax and abdomen bear five pairs of biramous appendages in each segment. The group shows diverse adaptation of the appendages. Basic structure of these limbs is modified for divergent function. It consists of proximal protopodite and two distal branches. Protopodite has coxa or coxopodite and a basis or basopodite. The latter has two elementsinner endopodite and outer exopodite, coxopodite extensions are called epipodites.

In most crustacean groups tagmatization includes the formation of a carapace on the cephalothorax. Appendages are associated with the functions of locomotion, respiration and feeding. Appendage adaptation may involve atrophy or hypertrophy of any of the basic elements described above. Respiration is either by gills or by body surface. Coelom is greatly reduced and forms haemocoel. Excretory organs are modified coelomoducts which may be either maxillary glands or antennary (green) glands. Heart lies in dorsal pericardial sinus which communicates by valvular ostia. Sexes are separate and show sexual dimorphism. Development includes metamorphosis with free larval stages.

6.5.2 Class Malacostraca

Malacostraca includes most of the larger forms such as crabs, lobsters, shrimps etc. and constitute the majority of crustacean species. The cephalic region is formed by the fusion of five segments; the trunk region consists of five thoracic and six abdominal segments. Additionally, a postabdominal telson forms part of the tail fin. A carapace covering the thorax may or may not be present. The thoracic appendages called paraeopods or walking legs have well developed endopodites used for crawling and prehension. The thoracic legs have gills, usually modified epipodites. In many malacostracans, first pair of thoracic appendages are modified into maxillepeds used for feeding. The first five pairs of abdominal appendages called pleopods are the swimming legs. Besides swimming, they may also be used for burrowing, carrying eggs in females and often for gas exchange. In males the first pair of abdominal appendages are modified as copulatory organs.

Malacostracans generally have a foregut modified as a two chambered stomach with triturating teeth and comblike filtering setae. The female gonopores are located on the sixth thoracic segment and the male gonopore on the eight. You have studied in Unit 8 of Block 2 of Animal Diversity course regarding the life cycle of malacostracans that includes many larval stages. 73

Animal Diversity: 1. Observation of Specimen of Palaemon (Prawn) Laboratory Examine the specimen in jar and note the following features:

i) Palaemon (Prawn) has a spindleshaped body which is bilaterally symemetrical. Size varies from 2.13 to 90 cm. ii) It is pale yellow in colour. Body is divided into anterior cephalothorax and posterior movable abdomen . iii) It possesses an exoskeleton of hard cuticle . iv) A continuous dorsal shield, covering cephalothorax is called carapace or dorsal plate which is a fused structure. Dorsal shield is produced into a rostrum . v) At the base of the rostrum on either side is an orbital notch which accommodates the stalk of compound eye. It also has two short spines on either side called antennal and hepatic spines respectively. vi) Hard pieces of skeleton covering abdomen are called sclerites . The sclerites are joined by membrane. vii) Mouth lies anteriorly as a midventral slit in the cephalothorax. viii) From the ventrolateral margins of each segment arises a pair of appendages or limbs. ix) Each appendage has protopodite or coxa and upper basopodite or basis. From the protopodite arise two rami i.e., an inner endopodite and outer exopodite .

Fig. 6.3: Palaemon .

x) There are nineteen pairs of biramous appendages consisting of antennules, antennae, mandibles and maxillae on head as cephalic appendages. Antennules bear statocyst on precoxa. Three pairs of thoracic appendages consist of maxillipedes. Cephalothorax also bears five pairs of walking legs . They perform multiple function of balancing, sensory, food handling, walking and swimming. Abdomen bears six pairs of pleopods . xi) Respiration is performed by epipodites or gills present in the anterior part of the gill chamber. xii) It is dioecious and shows sexual dimorphism.

Habit and Habitat Arthropoda: Observation and Found in fresh water ponds, ditches, lakes, streams and rivers. Nocturnal Classification of Specimens Hiding during the day and comes to surface at night.

Geographical Distribution: Commonly found in India.

Classification and its Justification

Kingdom Animalia Animals, multicellular organisms with cells that lack a cell wall, many capable of movement or movement of some of their body parts or capable of movement at some time of their life cycle; heterotrophic nutrition. Phylum Arthropoda Jointed appendages, segmented body. Subphylum Crustacea Biramous appendages. Class Malacostraca Thorax with walking legs, abdominal appendages are the swimming legs. Genus Palaemon Common Prawn Name

2. Observation of Specimen of Cancer (Crab) Examine the preserved specimen in jar. Sometimes dried specimens are also available (Fig. 6.4). Watch carefully for the following features: i) Cancer is commonly known as rockcrab or true crab. ii) Body is oval and flattened. iii) Cephalothorax is much broader compared to its length. iv) Eye stalks and antennules are found in the sockets of carapace. v) Antennae and antennules are small. vi) Third maxillipedes are broad, flat and valve like and cover the mouth parts. vii) There are 5 pairs of well developed thoracic legs. viii) The first pair of leg is chelate. ix) Abdomen is greatly reduced and lies permanently flexed in a groove on the very broad thoracic sterna. x) Pleopods happen to be much reduced, the male having only two pairs as copulatory organs, while females with four pairs for attachment of eggs. xi) Uropods are absent.

Habit and Habitat

Crab is found underneath rocks and sands. 75

Animal Diversity: Geographical Distribution : It is cosmopolitan in distribution, commonly found Laboratory in India, Europe and USA.

Classification and its Justification

Kingdom Animalia Animals, multicellular organisms with cells lacking cell walls, many capable of movement or movement of some of their body parts or capable of movement at some time of their life cycle; heterotrophic nutrition.

Phylum Arthropoda Jointed appendages, segmented body.

Subphylum Crustacea Biramous appendages.

Class Decapoda First three pairs of thoracic appendages modified as food capturing device, Gills enclosed in carapace.

Genus Caner

Common Rock-crab or Name true crab

Fig. 6.4: Cancer (Crab). 6.6 SUBPHYLUM UNIRAMIA

6.6.1 General Characters

The subphylum is called Uniramia because of the presence of unbranched appendages. These animals have nonjointed mandibles, unbranched appendages without any palps. They have only a single pair of antennae that correspond to the second cephalic segment (second antennae). Malpighian tubules act as excretory organs. This subphylum has 10,1300 species belonging to classes Chilopda, Pauropoda, Symphyla and Insecta. Here in this exercise we will study the class Chilopoda, class Pauropoda and class Insecta separately. 6.6.2 Class Chilopoda There are many trunk segments each bearing a single pair of legs. The head bears a single pair of antennae, mandibles and two pairs of maxillae. The 2 nd maxillae fuse to form a labium. A poison gland is also present in these animals.

Study of the specimen Scolopendra Arthropoda: Observation and Centipedes are active and aggressive carnivores (Fig. 6.5). About 3000 Classification of species have been discovered so far. These are found under surfaces of Specimens stones, soil and humus, and barks and logs.

Examine the specimen and note the following features: i) Centipedes feed on terrestrial invertebrates, worms, snails and other arthropods. ii) Body is elongated and dorsoventrally flattened. iii) Head is distinct and bears a pair of antennae, a pair of mandibles and two pairs of maxillae. iv) Trunk segments are numerous and each segment bears one pair of legs. The first pair of trunk legs are clawed and forwardly directed to form maxillipedes that bear a sharp claw connected with poison glands. v) Genital opening is situated at the hind end of the body. vi) Sexes are separate.

Fig. 6.5: Scolopendra .

Habit and Habit

Lives in soil and humus, beneath stones, barks and logs. Predacious.

Geographical Distribution: Inhabits both tropical and temperate regions of the world.

Classification and its Justification

Phylum Arthropoda Jointed appendages, segmented body.

Subphylum Uniramia Unbranched appendages.

Class Chilopoda Numerous trunk segments each bearing a pair of legs . 77

Animal Diversity: Genus Scolopendra Laboratory Species gigantica (large variety)

Common Centipede Name 6.6.3 Class Pauropoda

There are eleven trunk segments. The head bears one pair of antennae, one pair of mandibles and one pair of maxillae. Each trunk segment bears a pairs of legs and is devoid of blood vascular system and trachea. Study of specimen Julus

Examine the specimen of Julus and note the following features (Fig. 6.6):

i) Body consists of many segments.

ii) Head bears short sevenjointed antennae, a pair of maxillae and a pair of mandibles forming a gnathochilarium.

iii) On the dorsal surface there are six tergites which produce segmental coupling. This reduces undulations during movement.

iv) Heart and tracheae are absent. Direct diffusion of respiratory gases through the skin takes place.

v) Each trunk segment except the first four and last segment bears two pairs of legs.

vi) Poison jaws are absent, sting glands are present at the sides of the body.

vii) Sexes are separate, genital opening on the 3 rd segment behind the head.

Fig. 6.6: Julus .

Habit and Habitat

It lives in soil and humus and eat fungus and decaying matter. It is found rolled up under stones.

Geographical Distribution: Cosmopolitan, found in India. Arthropoda: Observation and Classification and its Justification Classification of Specimens Kingdom Animalia Animals, multicellular organisms with cells that lack a cell wall, many capable of movement or movement of some of their body parts or capable of movement at some time of their life cycle; heterotrophic nutrition.

Phylum Arthropoda Jointed appendages, segmented body.

Subphylum Uniramia Unbranched appendages.

Class Pauropoda Head bears antennae, one pair of mandibles, one pair of maxillae.

Genus Julus

Common Millipede Name 6.6.4 Class Insecta (Hexapoda)

You have already studied in theory course that insect body is distinctly divisible into head, thorax and abdomen. The head bears mouth parts, a pair of compound eyes and a pair of antennae; the thorax is threesegmented, generally with two pairs of wings and three pairs of jointed legs (hence also the name Hexapoda for the insects); the abdomen is usually 11 segmented and is devoid of appendages. You will study here two examples of this class. Study of specimen Periplaneta (Cockroach)

Fix a dried, preserved and wellstretched specimen of Periplaneta (Cockroach ) on a thermocol sheet and observe the following features (Fig. 6.7): i) The body is elongated, flattened dorsoventrally, bilaterally symmetrical with head broadly joined with the thorax. ii) The size of adult specimen ranges from 2.5 to 5.00 cm in length and 1.25 cm in width. iii) The body colour is reddish brown. The prothorax bears two dark patches surrounded by light brown margins. iv) Body is covered by a thick continuous exoskeleton. The dorsal, ventral and lateral coverings are known as tergum, sternum and pleuron respectively. v) Body is divided into head, thorax and abdomen. Head is connected to thorax by a slender neck or cervix. vi) Head bears numerous jointed appendages that are antennae, compound eyes and mouth parts. vii) Thorax is composed of three segments viz. prothorax, mesothorax, metatharax. From tergum of mesothorax arises a pair of fore wings, 79

Animal Diversity: while from the tergum of metathorax arises a pair of hind wings. Three Laboratory pairs of walking legs also arise from thorax.

viii) Abdomen is broad, dorsoventrally flattened and consists of 10 segments with no appendages.

ix) In both sexes 10 th segment bears ventrolaterally a pair of many jointed moveable anal cerci. However, in male 9th sternal plate carries a pair of unjointed styles in addition to a pair of anal cerci.

Fig. 6.7: Periplaneta americana.

Habits and Habitat

Cockroaches inhabitdark and damp places.

Geographical Distribution: Cosmopolitan in distribution.

Classification and its Justification

Phylum Arthropoda because it has a metamerically segmented body with jointed legs.

Class Insecta because its body is divisible into head, thorax and abdomen and thorax bears three pairs of legs.

Subclass Pterygota because wings are present and there is metamorphosis during development.

Order Orthoptera because it has biting and chewing type of mouthparts; the forewings are leathery, while hind wings are membranous.

Genus Periplaneta

Species americana

Common Cockroach Name

Study of specieman Apis (Honeybee) Arthropoda: Observation and General Account Classification of Specimens Honeybees are social and colonial insects found all over the world. Honeybees belong to the order Hymenoptera.

In India, three common species of honeybee are found namely Apis dorsata (wild bee), A. florea and A. indica . A. indica is the domesticated species for commercial beekeeping (apiculture).

Apis is characterized by two pairs of membranous wings and chewing and lapping mouth parts. The female has a poisonous sting. You can easily see a bee during flowering season of the year in the garden/park in your neighbourhood. The one you will see on a flower will be a worker bee. Its crop is modified into a honey sac and the ovipositor into the sting. The mouth parts, legs and wings show a high degree of specialization.

The honeybees feed on pollen and nectar of flowers and produce honey and beeswax. They communicate with each other through a sign language. Mating occurs in a nuptial (swarming) flight after which males die. Development occurs through complete metamorphosis including the following stages:

Egg Larva Pupa Adult

Eggs hatch on the third day but for completion of metamorphosis and emergence as an adult or imago it takes on an average 13 days for queen, 18 days for worker and 21 days for drone.

The individuals of a flourishing bee colony belong to three types of castes . There is usually a single fertile female or queen , a few hundred fertile males or the drones and the rest, sometimes in thousands, are the sterile females or the workers .

STUDY OF DIFFERENT CASTES OF HONEY BEE ( Apis indica/Apis dorsata ) – Worker, Queen, Drone

1) Worker bee

Nonreproducing female. Body divided into three parts i.e. head, thorax and abdomen. (Fig. 6.8)

Note the following features:

HEAD is a triangular structure and bears: i) a pair of compound eyes; ii) a group of three ocelli; iii) a pair of short jointed antennae, and iv) chewing and lapping type of mouthparts (a microscopic slide of the permanent mount of mouthparts of worker honey bee may be available to see the details) (Fig. 6.8).

THORAX is divided into three segments i.e. anterior prothorax, middle mesothorax and the posterior metathorax, each bears one pair of legs. 81

Animal Diversity: Mesothorax and metathorax carry a pair of wings on each. Laboratory LEGS

All the three pairs of legs are densely covered with hairs which aid in gathering pollen and are variously adapted. Each of the three legs shows some characteristic features.

A) Fore (prothoracic) legs

i) Eye brush on the distal part of tibia for removing pollen and other particles from the surface of the compound eye.

ii) Distal posterior end of tibia has velum and antennae comb to clean the antennae.

iii) Posterior face of the metatarsal segment bears bristles forming a pollen brush (Fig. 6.8).

B) Middle (Mesothoracic) legs

In mesothoracic legs, at the inner distal end of tibia is located a long spine like pollen spur . These are used to remove pollen from baskets and to dislodge wax from wax pockets on the ventral surface of the abdomen and transferring it for combbuilding (Fig. 6.8).

C) Hind (Metathoracic) legs

i) Pollen basket on the outer surface of tibia. It is a depression partially covered by rows of long curved bristles arising from its margin.

ii) Inner surface of the metatarsus bears a series of transverse rows of hard bristles forming the pollen combs (Fig. 6.8).

Fig. 6.8: Apis Honey bee.

WINGS Arthropoda: Observation and Two pairs of narrow wings, membranous and transparent. The two wings are Classification of coupled together by a series of minute hooks, called hamuli , so that they work Specimens together as one unit during flight.

ABDOMEN

Consists of six segments and bears the waxglands (on the underside) and the sting (at the end).

Wax-glands are modified cells on the ventral surface of the last four segments of abdomen.

Sting is the modified ovipositor .

Worker bees are sterile or neuter females arising from fertilised eggs laid by the queen and they live for 46 weeks.

The worker bees are repairers, keepers, feeders, fanners, foragers and defenders of the colony.

2) Queen bee (Fig. 6.8) i) Only fertile female with immensely developed ovaries. ii) Has elongated body with tapering abdomen and short legs and wings. iii) Mandibles, mouth parts and stings are shorter than those of the worker bee (Fig. 6.8). iv) Can not produce wax or honey. v) Can not collect nectar or pollen as legs are devoid of pollen basket, pollen brush etc. vi) Queen is specialized to lay eggs and is mother of all members of the hive. vii) Queen is a somewhat degenerated individual with a small brain and without salivary glands. viii) Arises from the fertilized egg and larva that is specially fed on “royal jelly”. ix) Lives for about 5 years and lays several hundreds of eggs per day.

3) Drones i) These are sexual male bees. ii) Have stouter and broader built. iii) Possess very large eyes and small pointed mandibles. iv) Devoid of wax glands, no pollen collecting apparatus and no sting. v) Develop parthenogenetically from the unfertilized eggs laid by the queen. vi) Function is only to mate with queen. 83

Animal Diversity: vii) Do not share any other job inside the hive. Laboratory viii) Cannot feed themselves, have to be fed by worker bees.

ix) Live for about five weeks.

Classification and its Justification

Phylum Arthropoda Bilaterally symmetrical, triploblastic and segmented. Body with chitinous exoskeleton. Jointed appendages.

Class Insecta Body differentiated into head, thorax and abdomen, 3 pairs of legs.

Division Endopterygota Wings develop internally and metamorphosis complete.

Order Hymenoptera Membranous wings, mouthparts rasping and lapping type (biting and sucking type), hind wings hooked to articulate with forewings.

Family Apidae

Genus Apis

Species indica

Common Honey bee Name 6.7 TERMINAL QUESTIONS

1. On what basis can you identify Limulus as belonging to the phylum arthropoda?

2. How would you define the subphylum crustacea in a single sentence?

3. What are the special features of Cancer so as to link it with class Arthropoda: Observation and Crustacea? Classification of Specimens

4. Sate in brief the advantages of biting and chewing type of mouth parts of cockroach.

5. List two most characteristic differences between centipedes and millipedes.

6. Define the term “polymorphism” in relation to social insects and name various castes of honey bees.