Animal Development and Body Plans

This set of flashcards summarizes key concepts related to animal development, symmetry, body plans, and various phyla, including sponges, cnidarians, and mollusks.

What is the difference between metamorphosis and growth and development in animals?

Metamorphosis involves a transformation into a different stage (e.g., caterpillar to butterfly), while growth and development refers to changes in size and physiology without a drastic transformation.

What types of symmetry are commonly observed in animals?

The two main types of symmetry are radial symmetry and bilateral symmetry.

Which phylum of animals is known to be asymmetric?

Sponges are the only phylum that exhibits asymmetry.

What does 'sessile' mean in terms of animal lifestyle?

Sessile animals are anchored in place and do not move, often relying on currents for feeding.

What type of symmetry allows an animal to respond evenly to stimuli from all directions?

Radial symmetry.

Define bilateral symmetry. What advantage does it provide?

Bilateral symmetry means the body can be divided into two mirror-image halves, allowing for directed movement and more developed sensory organs.

What are the two axes of orientation used in studying bilateral animals?

The head-tail axis (anterior-posterior, cranial-caudal) and the dorsal-ventral axis.

Which cells in sponges help create water currents for feeding?

Collar cells, also known as choanocytes.

What is a key characteristic of eumetazoans?

Eumetazoans have true tissues.

What are cnidarians and what body plans do they exhibit?

Cnidarians are animals like jellyfish and anemones that exhibit either a polyp (sessile) or medusa (free-floating) body plan.

What is the role of nematocysts in cnidarians?

Nematocysts are stinging cells that help cnidarians capture prey.

What are the advantages of having a centralized nervous system in bilateral animals?

A centralized nervous system allows for coordination of movement, sensory perception, and more complex behaviors.

What distinguishes rotary feeding mechanisms in animals like rotifers?

Rotifers use a specialized structure called a corona, which is a crown of cilia used for feeding.

How do some species of flatworms reproduce asexually?

Some flatworms can reproduce asexually by a process called fragmentation, where they can regenerate lost parts.

What is the primary difference between parasitic and free-living flatworms?

Parasitic flatworms often have complex life cycles and may require multiple hosts, whereas free-living flatworms are independent and typically do not rely on other organisms for their life cycle.

How do mollusks typically obtain oxygen for respiration?

Mollusks usually have gills that are located within their mantle cavity for gas exchange.