Question

A segmented worm has male and female reproductive organs in each segment. Some use hooks to attach to the intestinal wall. Which type of worm is this? a. fluke b. nematode c. cestode d. annelid

Short answer

c. cestode

Step-by-step solution

- Understand the Question

Identify the characteristics given: the worm has male and female reproductive organs in each segment, and some use hooks to attach to the intestinal wall.

- Analyze Each Option

Review each type of worm: a. Fluke: Flatworms with a complex lifecycle, often have suckers instead of segments. b. Nematode: Roundworms, typically not segmented. c. Cestode: Tapeworms, segmented with reproductive organs in each segment, and often use hooks to attach to hosts. d. Annelid: Segmented worms like earthworms, usually do not attach to intestinal walls using hooks.

- Eliminate Incorrect Options

Based on the given characteristics, eliminate fluke, nematode, and annelid: - Flukes do not have the described segmentation. - Nematodes are not segmented. - Annelids are segmented but do not match the reproductive and attachment methods described.

- Confirm the Answer

The remaining option is cestode. Cestodes are segmented worms (tapeworms) with reproductive organs in each segment, and they use hooks to attach to the intestinal wall.

Key concepts

cestode

Cestodes, commonly known as tapeworms, are a type of segmented worm categorized under the phylum Platyhelminthes. They specifically belong to the class Cestoda. Tapeworms are parasitic, relying on hosts such as humans and animals for survival. They exhibit a flat, ribbon-like body divided into segments called proglottids. Each proglottid contains a complete set of male and female reproductive organs, enabling them to reproduce effectively within the host.
Tapeworms lack a digestive system and absorb nutrients directly through their skin from their host's intestines. This parasitic adaptation allows them to thrive in nutrient-rich environments. Therefore, understanding the unique biology of cestodes is crucial for medical and veterinary science, as infestations can lead to severe health implications for the host.

reproductive organs in segmented worms

Segmented worms, particularly cestodes, exhibit a distinctive reproductive structure within each segment of their body. This structure includes both male and female reproductive organs, making them hermaphroditic. This means that a single tapeworm can self-fertilize, although cross-fertilization with other tapeworms may also occur.
The reproductive organs in each proglottid consist of testes (male organs) and ovaries (female organs). After fertilization, the eggs develop within the proglottids and are eventually released into the environment through segments that detach or break off from the worm. This dual reproductive capability greatly enhances their ability to spread and infect new hosts, ensuring their survival and perpetuation despite the hostile environment of the host’s digestive system.

intestinal wall attachment methods

Cestodes have evolved specialized structures for attaching to the intestinal walls of their hosts, ensuring they remain in place to absorb nutrients effectively. These structures include hooks and suckers located on the scolex (head) of the tapeworm. The hooks are tiny, claw-like structures that grip onto the intestinal lining. Meanwhile, the suckers create a vacuum-like seal to help the worm stay attached.
This dual attachment mechanism is vital for the cestode’s survival within the host. Through secure attachment, they can resist the peristaltic movements and other forces within the intestines. This close contact with the host's intestinal wall allows the tapeworm to absorb nutrients efficiently, supporting their growth and reproduction. Understanding these attachment methods is important for developing treatments and preventative measures against tapeworm infestations.