Phylum Annelida

Flashcards covering key concepts related to the Phylum Annelida, including taxonomy, anatomy, physiology, and reproduction.

Annelida includes approximately __ species of segmented worms.

20,000

Annelids are classified as __ organisms because they have a true coelom.

Eucoelomate

The mode of development in Annelida is known as __ development.

Protostome

Annelids inhabit all environments; terrestrial species require a __ environment.

moist

The defining characteristics of Annelids include one or more pairs of __ setae.

chitinous

Annelids are __ worms, consisting of repeated body sections.

segmented

The internal compartments of Annelids are separated by structures called __.

septa

Annelida typically exhibit __, which is the serial repetition of organs.

metamerism

Annelids are primarily characterized by their __ muscles, which allow movement.

longitudinal and circular

The __ system of Annelids is closed, featuring dorsal and ventral blood vessels.

circulatory

Annelids possess a well-developed __ system with dorsal cerebral ganglia and a ventral nerve cord.

nervous

The gut of Annelids is __, consisting of foregut, midgut, and hindgut.

complete

Annelids may have specialized structures for gas exchange like __ or gills.

dorsal cirri

The excretory organs found in Annelids are known as __, typically one pair per segment.

metanephridia

Annelids reproduce sexually or asexually; most marine forms are __, having separate sexes.

dioecious

In Annelida, __ refers to the reproductive process involving the exchange of sperm between hermaphrodites.

reciprocal sperm exchange

Leeches belong to the class __, which is part of phylum Annelida.

Hirudinea

Echiura, Siboglinidae, and Sipunulida are examples of groups that were absorbed into __.

Annelida

The __ are responsible for the filtering of waste in the excretory system of Annelids.

nephridia

The __ is the region where new segments are added in Annelids.

pygidium

Annelids have two main classes: Polychaeta and __.

Clitellata

Errantia and Sedentaria are two clades within the class __.

Polychaeta

The __ structure in clitellates enables mucus production for cocoon formation during reproduction.

clitellum

Hirudinea lack septa and have a fixed number of __ segments.

34

The __ in Leeches serves as a method for attachment to host organisms.

anterior sucker

Leeches produce a substance called __, which acts as an anticoagulant during feeding.

hirudin

The __ is often absent in Hirudinea, which distinguishes them from other Annelids.

well-developed sensory structures

Siboglinidae have a unique adaptation called a __, allowing them to house symbiotic bacteria.

trophosome

The anterior end of a Sipuncula is known as the __, which can be extended for feeding.

introvert

Echiura have a __ proboscis that aids in feeding.

ciliated

The gut of Sipuncula is __ in shape and provides a space for organ system arrangements.

U-shaped

Sipuncula species produce __ larvae that are a phase in their life cycle.

trochophore

Annelids carry out gas exchange primarily through their __.

body surface

The __ of Annelids functions as a muscular storage area for food digestion.

crop

Hirudinea are known as __ due to their feeding habits, which can include predation and parasitism.

ectoparasitic

Annelids have __ tissues that are derived from mesoderm.

coelomic

The __ keeps the coelom from collapsing in segmented worms during digestion and movement.

hydrostatic skeleton

The __ is a region behind the mouth where sensory structures can commonly be found in Annelids.

prostomium

Annelids include __, which have highly vascularized parapodia that assist in locomotion and gas exchange.

Errantia

The ventral nerve cord of Annelids contains segmental __, facilitating movement and coordination.

ganglia

Annelid excretion involves specialized structures called __ that are responsible for filtering coelomic fluid.

nephridia

In the reproductive cycle of Annelids, the __ larva is the stage where the organism has not yet developed into a mature adult.

trochophore

The __ of annelids serves a general function for sensory reception and detection of the environment.

head

The __ is formed early in the life cycle of Annelids, characterized by the presence of sensitive structures.

embryo

Annelids possess __ channels for blood flow and nutrient distribution throughout their bodies.

contractile

The __ connective tissues help in the organization of muscles and body support in Annelids.

peritoneal

Annelids employ __ for locomotion, which involve the coordination of longitudinal and circular muscles.

peristalsis

The __ in annelids is where the digestive tract ends, facilitating waste removal.

anus

The class __ within phylum Annelida encompasses most familiar marine worms.

Polychaeta

Hirudinea can utilize a __ for attachment, utilizing its muscle structure to grasp things.

posterior sucker

Annelids have developed a mechanism of __ for feeding, especially in sediment-dwelling species.

filter feeding

The __ in Errantia can help with locomotion and gas exchange; they are fleshy extensions from body segments.

parapodia

The __ of annelids conducts signals and aids in coordinating muscle contractions throughout the body.

ventral nerve cord

Hirudinea species often show __, which refers to a characteristic of having both male and female reproductive organs.

hermaphroditism

Some species of Annelids exhibit __, allowing them to regrow lost appendages or body parts after injury.

regeneration

The __ is a central point for many muscle group attachments, helping maintain body structure in annelids.

coelomic compartment

The __ provides structural support to Annelids' bodies but does not have anything solid inside, offering flexibility instead.

coelom

Annelids possess a __ which manages circulatory functions and transports oxygen via pigments.

closed circulatory system

Some Annelids exhibit __, which facilitates the exchange of substances from occurring on specialized body regions.

gas exchange through surfaces

The __ are the paired structures in some annelids, often found on the sides of segments that can extend.

tentacles

The development of sexual dimorphism in Annelida represents differences between and individuals in the species.

male; female

Annelids can be classified into two main clades based on their characteristics: and .

Errantia; Sedentaria

The __ circulates nutrients and helps provide tissue with essential compounds in Annelids.

blood

The nephridia in annelids are primarily responsible for maintaining __ balance and eliminating waste.

osmotic

The __ tissues in Annelids are crucial for movement and play an important role in their locomotion.

muscular

The __, a thickened part of the body wall, aids in forming a cocoon for reproduction in some Annelids.

clitellum

The anterior portion of cephalized annelids is known as the __, where most sensory organs are located.

head

Annelids lack __ in their buccal cavity, distinguishing them from many other marine organisms.

jaws

The Sipuncula, also called peanut worms, are characterized by having an __ introvert that can extend significantly.

anterior

The term __ is used to describe the evolutionary relationships among Annelids and their relatives, such as Siboglinidae.

phylogeny

Many Annelids undergo a life cycle process involving a __ to transition between juvenile and adult forms.

larval stage

Ocelli are sensory organs found in some _, helping them detect light changes in their environment.

Annelids

Clitellates are part of the larger group known as __, which also includes the polychaetes and leeches.

Annelida

The __ resistance in Annelids helps with their adapted survival in moist environments for respiratory exchange.

skin

Annelids have been witnessed exhibiting __, a behavior important in preening their setae and keeping clean.

self-grooming

The __ in the closed circulatory system of Annelids can redistribute blood effectively for various functions.

contractile vessels

Annelids can show a __ body plan, which refers to jointed body sections or segments continuing along length.

regional specialization

Annelids possess __ that help to keep skin hydrated, important for breathing through the skin surface.

mucus layers

In Annelids, __ structures can be found aiding in movement and sensory perception in the environment.

tentacular

Fossilized remains of Annelids indicate they have existed for hundreds of __ years, showing their evolutionary history.

millions

Annelids can often inhabit __ environments that range from aquatic to terrestrial ecosystems, showcasing diversity.

varied

Annelids display __ movement which is characterized by a wave-like ripple from head to tail.

sequential

In the classification of Annelids, the term __ describes a subclass within polychaetes which also includes sedentarians.

Clitellata

Regeneration in Annelids primarily focuses on __ segments after injury, restoring functions.

posterior

The __ circulatory system effectively transports nutrients acquired from feeding throughout the annelid body.

closed

The economic importance of Annelids includes their roles in soil fertility and __ health in ecosystems.

water quality

Annelids exhibit both a __ and sexual reproductive strategy for survival and species propagation.

asexual

Evolutionarily, Annelida shows lineage connections to mollusks, supporting __ relationships in both phyla.

phylogenetic

Annelids have a well-defined __ system for processing food and nutrient absorption through the digestive tract.

gastrointestinal