Protostomes 1 - Overview AND SPIRALIA/LOPHOTROCHOZOANS

Practice flashcards covering the classification, anatomy, and specific groups of Protostomes, including Lophotrochozoans (Spiralia) and Ecdysozoans.

Protostomes

A group of bilateral animals characterized by the blastopore developing into the mouth, an anterior brain surrounding the digestive tract, and a ventral nervous system.

Deuterostomes

A group of bilateral animals characterized by the blastopore developing into the anus.

Triploblastic

Animals possessing three embryonic cell layers, a characteristic of Bilaterians including Protostomes.

Acoelomate

An animal with no fluid-filled body cavity; the internal cavity is instead full of cells forming the mesenchyme.

Pseudocoelomate

An animal with an internal cavity full of fluid (pseudocoel) in which organs are suspended, with muscles only on the outside.

Coelomate

An animal with an internal cavity full of fluid (coelom) lined with a layer of tissue called peritoneum, which also covers the organs.

Peritoneum

A layer of tissue that lines the coelom and covers the internal organs in coelomate animals.

Hemocoel

A "blood chamber" found in arthropods that is part of the open circulatory system, allowing free circulation within the body.

Lophotrochozoa

One of the two main clades of protostomes; many members possess a trochophore larva or a feeding structure called a lophophore.

Ecdysozoa

One of the two main clades of protostomes; it contains animals that possess an external cuticle and must undergo molting (ecdysis) to grow.

Chaetognathes

Commonly known as arrow worms, these are predatory, marine, usually planktonic worms whose exact position within the protostomes is unclear.

Trochophore

A type of free-living larva characterized by bands of cilia, found in various Lophotrochozoans like Annelids and Molluscs.

Lophophore

A horseshoe-shaped crown of ciliated tentacles around the mouth used for filter-feeding in groups like Brachiopods and Bryozoans.

Spiralia

A synonym for Lophotrochozoa, named for the spiral cleavage (oblique division relative to the polar axis) that is a common condition in these animals.

Ecdysis

The process of molting or shedding an external cuticle to allow the animal to grow.

Platyhelminthes

Acoelomate flatworms that are dorsoventrally flattened; they lack a gas transport system and can be free-living or endoparasites.

Rotifera

Tiny multicellular animals (50-500 μm) with specialized internal organs, a complete gut, and a body cavity functioning as a hydrostatic skeleton.

Corona

A ciliated organ on the head of a rotifer where beating cilia sweep food particles into the mouth.

Mastax

An organ in rotifers used to grind food.

Bdelloid rotifers

A group of rotifers consisting only of females where eggs develop without fertilization, having existed for millions of years without sexual reproduction.

Bryozoans

Also known as "moss animals," these are sessile aquatic colonies made of many tiny zooids that construct an organic or calcareous colonial exoskeleton.

Cycliophora

Microscopic marine invertebrates discovered in 1995 that live on the mouthparts of lobsters.

Nemertea

Also known as ribbon worms, they possess a muscular proboscis for feeding and have a complete digestive tract.

Brachiopods

Solitary marine animals with two-part shells connected by a ligament; they use a lophophore for feeding and were most abundant in the Paleozoic and Mesozoic.

Annelida

Segmented worms restricted to aquatic or moist habitats, where the coelom in each segment is isolated from other segments.

Mollusca

A diverse group of animals including the largest known invertebrates; many have a calcareous shell and trochophore larvae.

Nematoda

Extremely abundant and universally distributed roundworms; some are microscopic while others, such as those found in sperm whale placentas, can reach length of $9\,m$.

Nematomorpha

Also known as "horsehair worms," their larvae are known to manipulate the behavior of hosts, such as crickets, to continue their life cycle in water.

Tardigrada

Commonly called "water bears," these extremely small animals have paired, fleshy, unjointed legs and live in marine sands or on water films on plants.

Onychophorans

Known as velvet worms, these are terrestrial animals with approx 200 species and paired, unstructured appendages.

Arthropods

The most abundant animal group, characterized by segmentation, jointed appendages, and a rigid exoskeleton providing support and protection.