Invertebrate Zoology: Introduction to Bilateria and Protostomia LN 10

These flashcards cover key concepts from the lecture on Invertebrate Zoology, focusing on the characteristics, classification, and ecological roles of basal bilaterians and specifically the phylum Xenacoelomorpha.

Basal Bilaterians

A group of simple, worm-like animals with bilateral symmetry, classified under Phylum Xenacoelomorpha.

Phylum Xenacoelomorpha

A taxonomic category of simple, acoelomate worms that exhibit bilateral symmetry and are considered the sister group to all other bilateral animals.

Acoelomate

An organism lacking a coelom or body cavity; characteristic of phylum Xenacoelomorpha.

Gastrovascular cavity

A cavity that serves both digestive and circulatory functions, present in some taxa but not all within Xenacoelomorpha.

Triploblastic

Referring to organisms made up of three primary germ layers: ectoderm, mesoderm, and endoderm.

Frontal organ

A secretory structure with glands that produce mucus, aiding in movement; initially thought to be chemosensory.

Cephalization

The development of a head with sensory organs and a centralized nervous system at the anterior end of the body.

Simultaneous hermaphrodites

Organisms that possess both male and female reproductive organs and can perform both roles in reproduction.

Ecological role of Xenacoelomorphs

These marine organisms are primarily deposit feeders, inhabiting sandy and gravel substrates, and can smother corals when populations are too large.

Ring furrow

A sensory structure on the body of Xenoturbellida resembling a pit filled with ciliated cells, thought to detect fluid flow.