Medusozoans and Hydrozoans

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Questions and Answers

Which characteristic is unique to lophophorates?

Utilization of a lophophore for feeding (correct)

Presence of a true coelom

Habitat restricted to freshwater

Reproduction through parthenogenesis

What are the two phyla included in the lophophorates group?

Annelida and Gastrotricha

Rotifera and Acanthocephala

Ectoprocta and Syndermata

Ectoprocta and Brachiopoda (correct)

What reproductive method do rotifers commonly use?

Parthenogenesis (correct)

Budding

Fission

Sexual reproduction

How do gastrotrichans primarily obtain their nutrients?

Feeding on decayed organic matter Signup and view all the answers

What sets acanthocephalans apart within the proposed phylum Syndermata?

Their parasitic lifestyle Signup and view all the answers

Which of the following characteristics is true about members of the clade Errantia?

They are characterized by the possession of parapodia. Signup and view all the answers

Which of the following statements is true regarding leeches?

Some leeches are known to be parasites that feed on blood. Signup and view all the answers

What distinguishes earthworms from leeches?

Earthworms extract nutrients from soil as they ingest it. Signup and view all the answers

What is a common reproductive strategy for earthworms?

They are hermaphrodites but usually cross-fertilize. Signup and view all the answers

Which of the following best describes sedentarians?

They are generally less mobile and may live in tubes. Signup and view all the answers

What are the two variations of the body plan found in Hydrozoans?

Polyp and medusa Signup and view all the answers

Which stage is predominant in the life cycle of scyphozoans and cubozoans?

Medusa Signup and view all the answers

What is the primary structural feature of the medusa body plan?

Bell-shaped with a mouth on the underside Signup and view all the answers

Which group includes only polyps and is considered most like the ancestral Cnidarians?

Anthozoans Signup and view all the answers

How do corals typically interact with algae?

They form symbiotic relationships Signup and view all the answers

Which method of reproduction involves producing a zygote?

Sexual reproduction Signup and view all the answers

What type of skeleton do corals secrete?

Exoskeleton Signup and view all the answers

What is the life cycle of Medusozoans characterized by?

Alternation between asexual and sexual reproduction Signup and view all the answers

Which characteristic differentiates nematodes from other invertebrate groups?

Presence of an alimentary canal Signup and view all the answers

What is the significance of Caenorhabditis elegans in scientific research?

It is a model organism for developmental biology Signup and view all the answers

Which group of organisms originated in the sea but now exclusively inhabit humid forests?

Onychophorans Signup and view all the answers

What unifying feature is characteristic of the phylum Arthropoda?

Segmented body with a hard exoskeleton Signup and view all the answers

Which statement accurately describes the evolutionary history of arthropods?

The arthropod body plan dates to the Cambrian explosion. Signup and view all the answers

What adaptation do tardigrades possess that allows them to survive extreme conditions?

Ability to enter a dormant state Signup and view all the answers

What is a common habitat for nematodes?

Aquatic environments and moist soil Signup and view all the answers

Which of the following describes a priapulan?

An organism dating back to the Cambrian period Signup and view all the answers

What type of digestive system do rotifers possess?

Complete alimentary canal Signup and view all the answers

Which of the following groups are considered coelomates with lophophores?

Ectoprocta Signup and view all the answers

What distinguishes Echinodermata from other animal phyla?

Radial symmetry as adults Signup and view all the answers

What is a unique characteristic of Chordata?

Possession of a notochord Signup and view all the answers

Which class of animals undergo ecdysis?

Nematoda Signup and view all the answers

Which group includes animals with jointed appendages and an exoskeleton made of chitin?

Arthropoda Signup and view all the answers

What type of body organization do acanthocephalans exhibit?

Parasites lacking a true body cavity Signup and view all the answers

What is the main characteristic of mollusks?

Three main body parts Signup and view all the answers

Study Notes

Hydrozoans

Hydrozoans have two basic body plans: polyp and medusa.
Polyps are sessile and attach to the substrate.
Medusae are free-swimming and bell-shaped.

Medusozoans

Medusozoans include scyphozoans (jellyfish), cubozoans (box jellyfish), and hydrozoans.
They have a gastrovascular cavity for digestion and circulation.
Mesoglea is a gelatinous layer between the epidermis and gastrodermis.

Medusozoan Life Cycle

The medusozoan life cycle involves both sexual and asexual reproduction.
Sexual reproduction involves the production of gametes and fertilization, resulting in a zygote.
Asexual reproduction occurs through budding of polyps.
The life cycle includes a planula larva that settles and develops into a polyp.

Anthozoans

Anthozoans include corals and sea anemones.
They only exist as polyps.
Many corals form symbiotic relationships with algae.
Corals possess a hard exoskeleton.

Lophophorates

Lophophorates include ectoprocts and brachiopods.
They are coelomates with a lophophore, a feeding structure with ciliated tentacles.

Rotifers and Acanthocephalans

Rotifers and acanthocephalans are now classified together as the phylum Syndermata.
Rotifers are tiny animals with a pseudocoelom and a complete digestive system.
They reproduce through parthenogenesis.

Gastrotricha

Gastrotricha are small "hairy-belly" worms that live in aquatic environments.
They feed on decayed organic matter.

Cycliophora

Cycliophora are a phylum discovered in 1995.
They are symbiotic with lobsters, living on their mouthparts.

Nemertea

Nemertea, or ribbon worms, lack a coelom but have a gut.
They have a blood vascular system without a heart.

Annelida

Annelids are coelomates with segmented bodies.
They are divided into two major clades: Errantia and Sedentaria.

Errantia

Errantians are mostly mobile marine predators or grazers.
They possess parapodia with chaetae (bristles) for locomotion.

Sedentaria

Sedentarians are less mobile than errantians.
They include tube-dwelling species and leeches.
Some have gills or tentacles for filter feeding.

Leeches

Leeches are mostly found in freshwater environments.
Some are predators of invertebrates, while others are blood-sucking parasites.
They produce hirudin, a chemical that prevents blood clotting.

Earthworms

Earthworms are decomposers that consume soil.
They are hermaphrodites but cross-fertilize.
They can reproduce asexually through fragmentation.

Priapulans

Priapulans are marine worms with a distinctive body shape.
They are coelomates with a complete digestive system.
They have been found in Cambrian fossils.

Onychophora

Onychophora, or velvet worms, are terrestrial predators found in humid forests.
They have a segmented body with numerous legs.
They have a unique slime-shooting defense mechanism.

Tardigrada

Tardigrada, or water bears, are extremely small animals with four pairs of legs.
They are known for their extreme resilience and ability to survive harsh conditions.
They can survive freezing, desiccation, and radiation.

Nematoda

Nematodes, or roundworms, are pseudocoelomates with a cylindrical body shape.
They have a complete digestive system but lack a circulatory system.
They are found in a wide range of habitats, including soil, water, and the bodies of plants and animals.

Arthropoda

Arthropoda is the largest phylum in the animal kingdom.
They are coelomates with a segmented body, jointed appendages, and a hard exoskeleton.
They have a wide range of adaptations and occupy diverse ecological niches.

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Description

Explore the fascinating world of hydrozoans and medusozoans through this quiz. Learn about their distinct body plans, reproduction methods, and life cycles. From polyps to jellyfish, discover the diverse forms of these marine organisms.