Test of Practical on Worms: Platyhelminthes (Tapeworm), Nematodes, And Annelids (Earthworm)

SPECIMEN: Whole Tapeworm Freshly Preserved

Identify

• Tapeworm

Reasons:

• Presence of Scolex (Small head called scolex)
• Dorsoventrally flattened body
• Long tape-like body (ribbon-like body)
• Presence of progttides.

Observable features of Tapeworm

• Scolex
• Four suckers
• Double row of hooks
• Dorsoventrally flattened body
• Long tape-like body

Observable Adaptive Features of Tapeworm.

• Presence of suckers and hooks to attach the organism to the host
• Dorsoventrally flattened and long body provides a large surface area for absorption of food nutrients from the host by diffusion because it lacks a vascular system
• Proglottids contain eggs for dispersal
• Thick cuticle for protection against digestion by host enzymes
• Elongated body divided into proglottids, which can break off

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Mode of Reproduction.

• Mature proglottids (at the tail end) contain ripe fertilised eggs
• Mature proglottids containing fertilised eggs break off
• And are passed out with faeces of the host

Biological Classification

Phylum Platyhelminthes

Reasons:

• Presence of a flat, unsegmented body
• Triploblastic,
• Acoelomate
• Bilateral symmetry
• No vascular system

Class Cestoda

Reasons:

• Have a flattened segmented body divided into proglottids
• Thick cuticle covers the body (because they are endoparasites)
• The head is called the scolex, with suckers and hooks
• Gut is absent

Habitat:

• Endoparasite in the small intestine of mammals

Adaptations to live in its habitat

• Cuticle resists digestion by host enzymes
• Hooks and suckers attach the organism to the intestines of the host
• Hooks for attachment to the small intestine of the host
• Four Suckers for attachment to the small intestine of the host
• Proglottids contain eggs for dispersal
• Flat and long body provides a large surface area for absorption of nutrients

Reproduction:

• Sexual hermaphroditism by self-fertilisation

Reason:

• Proglottis has both male and female reproductive structures

Host of the Specimen.

• A human being is the primary host because the sexual activities of the specimen occur in humans
• Secondary hosts: cow, pig

Effects of the specimen on the host

• Reduced growth. It is deprived of its nutrients
• The parasite may produce toxic substances which may harm the host.
• The parasite destroys some cells of the host; as a result, the host may be weak, sick and eventually die.

Excretory organ:

• flame cell

Feeding habit:

• Parasitic (but not parasitism)

Reason:

• Presence of hooks and suckers for attachment to the host
• Presence of a flat body with a large surface area for absorption of digested food

Economic Importance of Tapeworm

• Parasites on farm animals, hence reducing their yield
• Causes diseases in farm animals
• Attacks human
• Causes death

Prevention and control of tapeworm infestation:

• Examine meat
• Cook the meat well
• Dispose of faeces well
• Keep animals away from faeces
• Take recommended drugs (Deworming)

NEMATODS (ROUND WORM)

SPECIMEN: A round worm obtained from the slaughtering house and put in a petri dish

Biological classification

Phylum Nematoda

Reason:

• Unsegmented body
• Bilaterally symmetrical
• Cylindrical body
• The body is pointed at both ends
• Triploblastic, Pseudocoelomate
• Have a gut with the mouth and anus
• The body is pointed at both ends
• Are dioecious: separate sexes

Observable Features of Interest

• Cylindrical body
• Pointed ends

Mode of nutrition:

• Parasitic

Habitat:

• Small intestine of farm animals/mammals
• Cow,
• Human

As parasite of farm animals enjoys;

• Food
• Shelter
• Protection
• Warmth

Effects of the organism on its host

• Reduced growth: It is deprived of its nutrients
• Diseases: The parasite may produce toxic substances which may harm the host.
• Death: The parasite destroys some cells of the host; as a result, the host may be weak, sick and eventually die.

Control methods

• Deworm farm animals regularly.
• Ensure the food hygiene of farm animals

EARTHWORM (ANNELIDS)

SPECIMEN: Freshly preserved earthworm.

Biological classification.

Phylum: Annelida

Reasons:

• Metameric segmentation
• Triploblastic, Coelomate
• Cylindrical body
• Body tapers at both ends (note: not the term pointed)
• Presence of chaetae on each body segment

Class Oligochaeta

Reasons:

• Presence of clitellum
• Few chaetae/setae on the segment, but no parapodia
• No distinct head and no eyes

Observable characteristics of earthworms

• Few chaetae/setae on each segment
• Metameric segmentation
• Body tapers at both ends
• Moist, slimy and soft flexible body (presence of mucus makes the surface moist and slimy)
• Cylindrical body
• Darker dorsal body
• Each segment except the first and the last bears chaetae for locomotion, hence a rough surface when rubbed with your finger.
• Clitellum: 32nd-37th segment from the head (about 1/4th the length from the mouth)
• Excretory pores
• Reddish colour on the surface due to the presence of blood capillaries
• Skin is moist: Glands in the skin keep the body moist to allow gaseous exchange

Habitat:

• moist soil
• burrows in moist soil
• leave litter

Locomotory method:

• Peristaltic

Locomotory structure:

• Chaeta

Mode of nutrition:

• Holozoic

Method of feeding:

• Detritivorous, thus feeds on dead leaves/grasses, and soil

Feature for feeding:

• Prostomium/mouth

Reproduction:

• Sexual/ hermaphroditic with cross-fertilisation.
• Exhibits oviparity (lays eggs).

Respiratory structure:

• Skin

Excretory structure:

• Nephridium

Type of skeleton:

• Hydrostatic (water/ coelomic fluid)

Adaptive features of the earthworm to its habitat

• Tapering anterior and posterior ends to push through litter.
• A flexible body facilitates wriggling through litter.
• Chaetae for gripping the substratum to avoid slipping during locomotion
• Moist body for gaseous exchange and lubrication in movement.
• Moist body to provide lubrication for easy movement.
• Moist mucus body kills bacteria and fungi.
• Clitellum for copulation and cocoon formation
• Cuticle secreted by the epidermis protects against desiccation.

Describe the reproductive process in earthworms.

• Monoecious with cross-fertilisation:
• This means each individual has both male and female organs but cannot fertilise itself (cannot undergo self-fertilisation). Hence, the exchange of sperm between two individuals,
• Two mates with their heads pointed in opposite directions
• The two are glued with mucus from the clitellum
• Each member then receives sperm from the other partner and stores them in the seminal vesicle that occurs between the clitellum and head region (9th and 10th segments).
• When the two separate,
• The clitellum forms a cocoon
• Eggs are deposited into the cocoon.
• Cocoon then slips away towards the head
• When it passes the seminal vesicle, sperm are discharged to fertilise the eggs
• Cocoon is then slipped off and deposited in damp soil

Adaptive features for defence

• Moist mucus to kill bacteria and fungi
• Dark dorsal surface blends with dark soil
• Darker dorsal body blends with the environment

Functions of clitellum

• For attachment during the exchange of sperm (copulation)
• It aids in copulation and cocoon formation

Function of chaetae

• For gripping substratum during movement/ so that the organism does not slip

Function of the cocoon:

• Carries eggs

Economic Importance of Earthworm

• Aerates the soil by burrowing
• Turns the soil, thereby improving soil texture and adding nutrients.
• Increases humus content by cutting the leaf into pieces, providing a large surface area for the enzymes of bacteria and fungi
• Loosens soil for easy passage of roots
• Increases drainage to prevent the soil from becoming waterlogged
• Mucilage binds soil particles, thereby improving soil texture

Agricultural importance of earthworms

• Its mucilage binds soil particles to improve soil structure
• Faecal pellets improve soil texture
• Burrowing improves aeration of the soil
• Increases humus content by cutting the leaf into pieces, providing a large surface area for the enzymes of bacteria and fungi.

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