Biology Tubellarians Overview

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Questions and Answers

What is one common feature of Tubellarians?

They possess light-sensitive eye spots. (correct)

They have leaf-like bodies.

They lack tactile and chemoreceptor cells.

They exclusively reproduce asexually.

Which of the following is true about the reproductive methods of Tubellarians?

Tubellarians cannot reproduce sexually.

Tubellarians reproduce solely by fission.

They are only capable of asexual reproduction.

They are hermaphroditic and exchange gametes. (correct)

What term is used to describe the cavity that lacks a peritoneal lining in true coelomates?

Hemocoel

Pseudocoel (correct)

Acoelom

Coelom

What characterizes the adult Trematoda in terms of anatomy?

They have cylindrical or leaf-like shapes. Signup and view all the answers

Which statement about the life cycle of Trematodes is accurate?

Eggs are shed in water and can infect intermediate hosts. Signup and view all the answers

How many species of roundworms (Phylum Nematoda) have been described so far?

12,000 Signup and view all the answers

What is eutely in nematodes?

Constant number of cells during growth Signup and view all the answers

Which of the following Trematodes is known to infect humans?

All of the above Signup and view all the answers

What is the primary role of molluscs in the life cycle of Trematodes?

They act as intermediate hosts for asexual reproduction. Signup and view all the answers

What type of nematodes primarily feeds on bacteria, yeast, and plant juices?

Free-living nematodes Signup and view all the answers

How long can individual flukes of Clonorchis sinensis live in humans?

15-30 years Signup and view all the answers

What is a common method of infection for parasitic nematodes?

Eating poorly-cooked meat containing larvae Signup and view all the answers

Which of the following nematodes is known to cause trichinosis?

Trichinella spiralis Signup and view all the answers

What forms the basis of the classification of Trematodes into tissue flukes and blood flukes?

The system or organs they infect in the host. Signup and view all the answers

What is the usual reproductive method of nematodes?

Sexual reproduction Signup and view all the answers

What is a significant ecological role of nematodes in their environments?

Decomposing organic materials Signup and view all the answers

What type of circulatory system is present in most molluscs?

Open circulatory system Signup and view all the answers

Which mollusc group is noted for reaching the largest size?

Cephalopods Signup and view all the answers

What is the primary function of the radula in molluscs?

Feeding Signup and view all the answers

Which part of the molluscan body plan is responsible for digestive and reproductive functions?

Visceral mass Signup and view all the answers

What are the two folds of skin that form a protective layer in molluscs called?

Mantle Signup and view all the answers

What is the outer layer of a molluscan shell called?

Periostracum Signup and view all the answers

What type of reproduction is typically seen in most molluscs?

Dioecious reproduction Signup and view all the answers

What are the two larval stages that molluscs may go through during development?

Trochophore and Veliger Signup and view all the answers

What is the primary characteristic of the Class Caudofoveata?

They have a burrowing lifestyle with no shells. Signup and view all the answers

Which mollusc class is known for having 8 articulating plates?

Class Polyplacophora Signup and view all the answers

Which class of molluscs has no radula or gills?

Class Solenogastres Signup and view all the answers

What process do bivalves primarily use to feed?

Sedentary filter feeding using ciliary currents. Signup and view all the answers

Which mollusc class was thought to be extinct until it was rediscovered in 1952?

Class Monoplacophora Signup and view all the answers

What is a unique feeding adaptation of the Class Polyplacophora?

A reinforced radula made with magnetite. Signup and view all the answers

Which of the following statements is true about Class Bivalvia?

Bivalves have laterally compressed bodies with two shells. Signup and view all the answers

Which of the following is a significant factor in the locomotion of bivalves?

Use of jet propulsion through a muscular foot. Signup and view all the answers

What is one of the most dangerous consequences of worms encysting in the human body?

Respiratory paralysis Signup and view all the answers

Which of the following nematodes is known to attack garden plants?

Root-knot nematodes Signup and view all the answers

How can predatory nematodes be bred for use as pest control?

By soaking specific leaves in water and keeping it dark and cool Signup and view all the answers

Which phylum is described as having about 250 species, known as 'horsehair worms'?

Nematomorpha Signup and view all the answers

What is a unique characteristic of phylum Kinorhyncha?

They have a complete digestive tract and sensory eyespots Signup and view all the answers

What is a key feature of phylum Loricifera?

They possess tiny protective cases called lorica Signup and view all the answers

Which characteristic is NOT true for the phylum Priapulida?

They are all less than 1mm long Signup and view all the answers

What distinguishes Rotifera from other phyla?

They possess a characteristic ciliated 'crown' or corona Signup and view all the answers

Study Notes

Active Locomotion and Nervous System

Active locomotion in organisms promotes cephalisation, enhancing nervous system complexity.
Light-sensitive eyespots (ocelli) prevalent in Tubellarians and larval trematodes aid in environmental awareness.
Auricles on the heads of planarians contain tactile and chemoreceptor cells, enhancing sensory perception.

Reproductive Strategies and Regeneration in Tubellarians

Tubellarians can reproduce both sexually and asexually, with fission as a common asexual method.
They possess remarkable regenerative abilities; excised tissue can regenerate a complete individual.
Tubellarians are hermaphroditic, requiring gamete exchange with another individual for reproduction.

Trematoda Overview

Trematodes consist of an estimated 18,000 to 24,000 species, most of which are parasitic.
Commonly include leaf-like or cylindrical bodies without cilia, with ventral suckers for attachment.
Alimentary canal features two main branches for digestion.

Classification of Trematodes

Divided into tissue flukes (e.g., Paragonimus westermani, Clonorchis sinensis) and blood flukes (e.g., Schistosoma species).
Tissue flukes infect bile ducts, lungs, or various biological tissues, while blood flukes inhabit the blood.

Life Cycle and Infection of Trematodes

Complex life cycles involving molluscs as intermediate hosts, with a mix of sexual and asexual reproduction.
Eggs are shed in feces, hatch in water releasing infective larval forms targeting intermediate hosts.
Human infections can occur through consumption of undercooked infected fish or direct exposure.

Nematoda (Roundworms) Characteristics

Phylum Nematoda includes 12,000 described species, potentially up to 500,000 worldwide.
Habitat diversity ranges from marine to freshwater and soil environments.
Eutely phenomenon characterized by a constant cell number as individuals grow larger.

Nematodes as Parasites and Ecological Role

Nematodes are prevalent parasites affecting various plants and animals, significantly impacting agriculture.
Free-living nematodes feed on organic material and are prey to larger organisms, playing crucial ecological roles.

Reproduction and Life Cycle of Nematodes

Sexual reproduction is typical, with males often smaller and adapted for copulation.
Complicated life cycles are common in parasitic forms, involving multiple hosts and varying infection routes.

Trichinosis and Other Human-affecting Nematodes

Trichinella spiralis causes trichinosis, leading to gastrointestinal and systemic symptoms after consuming infected meat.
Other common human parasitic nematodes include whipworms, hookworms, pinworms, and filarids (e.g., Wuchereria bancrofti).

Unique Phyla within Ecdysozoa

Horsehair worms (Nematomorpha) are free-living as adults and parasitic during juvenile stages, featuring vestigial digestive systems.
Kinorhyncha are tiny (less than 1 mm), segmented, and adapted to various marine environments.
Loricifera, recently described, are less than 0.25 mm, possessing a protective case and living between sand grains.

Molluscan Anatomy and Physiology

Mollusks have evolved complex structures, including a 'head-foot' region for sensory and locomotor functions, and a visceral mass for organ systems.
A protective mantle surrounds the mantle cavity, which houses gills or lungs and can secrete a shell in many species.

Molluscan Diversity and Classes

Ten classes of molluscs exist, with 250,000+ species; some classes include:
- Caudofoveata: Deep-sea worm-like creatures with no shells, radula present.
- Bivalvia: Includes clams, oysters, and mussels, characterized by two shells and lack of a radula.
- Polyplacophora: Chitons with dorsal plates, adapted for rocky shorelines.

Life Cycle and Larval Stages

Molluscs exhibit free-swimming larval stages: trochophores and sometimes veligers in more advanced groups.
Direct juvenile hatching occurs in cephalopods and some others, eliminating the larval stage.

Ecological Significance of Nematodes

Nematodes can be beneficial, such as predatory species that reduce pest populations, or harmful, affecting crops and livestock.
Predator-prey dynamics involving nematodes play significant roles in ecosystem functioning and agriculture.

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Description

This quiz delves into the unique characteristics of Tubellarians, focusing on their nervous system development, sensory organs, and reproductive methods. Explore the fascinating features like eyespots, tactile cells, and their remarkable regenerative abilities. Perfect for students studying biology and invertebrate systems.