Echinoderms Quiz
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__________ are members of the phylum Echinodermata.

Sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers, and their relatives

All echinoderms are __________.

marine

They are the only animals that have a __________.

water-vascular system

The water-vascular system consists of __________.

<p>a madreporite, a series of canals, ampullae, and tube feet</p> Signup and view all the answers

Echinoderms also have an endoskeleton that is embedded in the __________ portion of the skin.

<p>dermis</p> Signup and view all the answers

The pieces of the endoskeleton are referred to as ossicles and are made of __________.

<p>calcium carbonate</p> Signup and view all the answers

__________ of various species differ in shape and may or may not be fused together.

<p>Ossicles</p> Signup and view all the answers

If the ossicles are not fused they often form a lattice network bound together by __________.

<p>connective tissue</p> Signup and view all the answers

However the __________ of sea cucumbers are very small and scattered.

<p>ossicles</p> Signup and view all the answers

Ossicles that fit together compactly and that are fused are often referred to as __________.

<p>plates</p> Signup and view all the answers

Species with __________ have a rigid skeleton.

<p>fused plates</p> Signup and view all the answers

Spines extend from some of the __________ of most species of echinoderms.

<p>ossicles or plates</p> Signup and view all the answers

Adults are benthic and depending on the species are __________ symmetrical.

<p>radially, biradially, or bilaterally</p> Signup and view all the answers

Concerning the nervous system they lack a brain, nerves extend out from one or more __________.

<p>nerve rings</p> Signup and view all the answers

The peritoneum is ciliated and __________ flows as a result of ciliary action.

<p>coelomic fluid</p> Signup and view all the answers

Respiratory gases and nutrients are transported mainly by __________ and to a lesser extent by the __________.

<p>coelomic fluid, blood</p> Signup and view all the answers

Most species are __________ and __________ fertilization occurs.

<p>dioecious, external</p> Signup and view all the answers

The __________ of the gastrula stage of echinoderms, hemichordates and chordates becomes the anus.

<p>blastopore</p> Signup and view all the answers

In contrast, the blastopore of members of the phyla studied previously (phylum Mollusca) becomes the __________ if they have a __________.

<p>mouth, protostome</p> Signup and view all the answers

The larvae are __________ and are usually __________.

<p>bilaterally symmetrical, planktonic</p> Signup and view all the answers

Members of each class produce one or more kinds of __________ larvae.

<p>ciliated</p> Signup and view all the answers

They have arms that are not sharply set off from the __________.

<p>central disc</p> Signup and view all the answers

There is an __________ on each arm.

<p>ambulacral groove</p> Signup and view all the answers

They have spines; __________ belong to this class.

<p>sea stars (starfish)</p> Signup and view all the answers

A __________ larvae develops that later becomes a __________ larvae.

<p>bipinnaria, brachiolaria</p> Signup and view all the answers

They have arms that are sharply set off from the __________.

<p>central disc</p> Signup and view all the answers

They do not have __________.

<p>ambulacral grooves</p> Signup and view all the answers

They have spines. __________ belong to this class.

<p>Brittle stars and basket stars</p> Signup and view all the answers

They typically have an __________ larva stage.

<p>ophiopluteus</p> Signup and view all the answers

They do not have __________.

<p>arms</p> Signup and view all the answers

The endoskeleton consists of __________ and is rigid.

<p>fused plates</p> Signup and view all the answers

They have spines; each spine has a __________ at its base that fits over a tubercle on a plate and is moved by __________ at its base.

<p>concave socket, small muscles</p> Signup and view all the answers

Since a __________ joint is present their spines are highly maneuverable.

<p>ball and socket</p> Signup and view all the answers

__________ belong to this class.

<p>Sea urchins, sand dollars, cake urchins, and heart urchins</p> Signup and view all the answers

They have an __________ larva stage.

<p>echinopluteus</p> Signup and view all the answers

They do not have __________. They do not have __________.

<p>arms, spines</p> Signup and view all the answers

__________ belong to this class.

<p>Sea cucumbers</p> Signup and view all the answers

Sea cucumbers; They have an __________ larva that later becomes a __________ larva.

<p>auricularia, doliolaria</p> Signup and view all the answers

They have __________, there is an __________ on each arm.

<p>arms, ambulacral groove</p> Signup and view all the answers

They do not have __________.

<p>spines</p> Signup and view all the answers

__________ belong to this class.

<p>Crinoids</p> Signup and view all the answers

Two categories of them are __________.

<p>sea lilies, feather stars</p> Signup and view all the answers

They have __________ larva stage.

<p>doliolaria</p> Signup and view all the answers

In some species the doliolaria is preceded by an __________.

<p>auricularia</p> Signup and view all the answers

These animals are __________ shaped.

<p>star</p> Signup and view all the answers

Their bodies consist of arms attached to a __________.

<p>central disc</p> Signup and view all the answers

Most species have __________ arms.

<p>five</p> Signup and view all the answers

Their __________ increase in width from the apex to the base.

<p>arms</p> Signup and view all the answers

Many tube feet extend from an __________ on the underside of each arm.

<p>ambulacral groove</p> Signup and view all the answers

__________ of these animals function for locomotion and for handling food.

<p>Tube feet</p> Signup and view all the answers

Tube feet and other components of the water-vascular system are as follows: __________.

<p>Madreporite, stone canal, ring canal, radial canal, lateral canals, ampullae, tube feet, Tiedemann's bodies, polian vesicles for some</p> Signup and view all the answers

The __________ is located on the aboral surface of the central disc.

<p>madreporite</p> Signup and view all the answers

The surface of the madreporite has __________ on it.

<p>furrows</p> Signup and view all the answers

Many pores are present at the bottom of each __________.

<p>furrow</p> Signup and view all the answers

Water passes in and out of it through the __________.

<p>pores</p> Signup and view all the answers

This allows for adjustments to be made to changes in __________ that result from depth differences due to tidal fluctuations.

<p>water pressure</p> Signup and view all the answers

Canals of the water vascular system are lined with __________ epidermis.

<p>ciliated</p> Signup and view all the answers

Little pouches called __________ are attached to the ring canal.

<p>Tiedemann's bodies</p> Signup and view all the answers

Tiedemann's bodies produce phagocytic cells called __________ which remove bacteria and other foreign matter from incoming water.

<p>coelomocytes</p> Signup and view all the answers

Some water and coelomocytes pass through Tiedemann's bodies into the __________.

<p>coelom</p> Signup and view all the answers

Little sacs called __________ are also attached to the ring canal of some species. They function for fluid storage.

<p>polian vesicles</p> Signup and view all the answers

Concerning locomotion, longitudinal muscles on one side of tube foot contract, which cause it to bend in that direction; then as the __________ contracts, a valve in the lateral canal closes and water is forced into the tube foot which elongates.

<p>ampulla</p> Signup and view all the answers

Contraction of __________ muscles in the tube foot forces water back into the ampulla and tube foot shortens. This process is continually repeated.

<p>longitudinal</p> Signup and view all the answers

All of the __________ move in the same direction but not in unison.

<p>tube feet</p> Signup and view all the answers

As many tube feet shorten the animal is slowly pulled __________.

<p>forwards</p> Signup and view all the answers

The tube feet of most species have a __________ at the distal end.

<p>sucker</p> Signup and view all the answers

When a __________ comes in contact with hard substrate such as a rock, the sucker adheres; when on mud or sand the tube feet function as legs (no suction).

<p>tube foot</p> Signup and view all the answers

__________ cells are scattered in the epidermis.

<p>Tactile and chemoreceptor</p> Signup and view all the answers

An __________ is located at the tip of each arm.

<p>eye spot</p> Signup and view all the answers

Most species feed on __________.

<p>slow moving prey, sessile prey and dead animals</p> Signup and view all the answers

Some feed mainly on __________; when doing so a sea star humps over its prey, attaches its tube feet to the valves, and pulls.

<p>bivalve molluscs</p> Signup and view all the answers

When the valves separate, the sea star everts its __________ through its mouth and wraps it around the soft parts of the bivalve.

<p>stomach</p> Signup and view all the answers

Digestive enzymes are released and the soft parts of the prey are converted into a __________, then the sea star pulls in its stomach.

<p>thick broth</p> Signup and view all the answers

Digestion continues within the __________.

<p>stomach and pyloric ceca</p> Signup and view all the answers

There is one pair of __________ per arm.

<p>pyloric ceca</p> Signup and view all the answers

The body wall consists of __________.

<p>epidermis, dermis that contains ossicles, circular muscles, longitudinal muscles, and peritoneum</p> Signup and view all the answers

Respiration and excretion occur through __________ and to a lesser extent through the tube feet.

<p>papulae</p> Signup and view all the answers

Papulae are __________ of the body wall, where they are present the peritoneum extends outward between the ossicles and is almost in contact with the epidermis. The dermis here is very thin and muscle tissue is absent.

<p>evaginations</p> Signup and view all the answers

Oxygen diffuses in and carbon dioxide diffuses out through the __________.

<p>papulae</p> Signup and view all the answers

Also __________ and other soluble metabolic waste diffuse out through them (papulae).

<p>ammonia</p> Signup and view all the answers

Amoeboid cells called __________ engulf particulate waste and either exit the body through the papulae or the tube feet.

<p>coelomocytes</p> Signup and view all the answers

These animals have minute pincer-like structures called __________ that keep the body surface free of debris and small animals that settle there so that respiration and excretion are not hindered.

<p>pedicellariae</p> Signup and view all the answers

Each pedicellaria consists of a __________ and __________.

<p>stalk, jaws</p> Signup and view all the answers

The stalk portion can extend, retract, and bend; when the jaws are touched on the outside they snap __________, when touched on the inside they snap __________.

<p>open, shut</p> Signup and view all the answers

They also snap shut in response to __________ stimuli.

<p>chemical</p> Signup and view all the answers

The pedicellariae pinch and cut or break up __________ which are then moved off the body surface as cilia of epidermal cells beat.

<p>tiny animals and debris</p> Signup and view all the answers

Two __________ are located in each arm. They are large and filled with gametes; otherwise, they are quite small.

<p>gonads</p> Signup and view all the answers

Sea stars __________ missing parts and can also undergo autotomy.

<p>regenerate</p> Signup and view all the answers

__________ refers to the deliberate breaking off of an injured part of the body by the organism itself; for these animals, it refers to casting off an arm.

<p>Autotomy</p> Signup and view all the answers

Many species can regenerate a complete sea star from a detached arm that contains about __________ of the central disc.

<p>one fifth</p> Signup and view all the answers

In the past, mops were dragged through oyster beds and the starfish that were collected were chopped up with a hatchet or knife and thrown back into the water; instead of destroying them, this had the __________ effect.

<p>opposite</p> Signup and view all the answers

These animals are __________ shaped.

<p>star</p> Signup and view all the answers

Their bodies consist of arms attached to a __________.

<p>central disc</p> Signup and view all the answers

All organs of their digestive and reproductive system are located within the __________.

<p>central disc</p> Signup and view all the answers

Their arms are slender and fragile. Most species have __________ arms.

<p>five</p> Signup and view all the answers

Each arm contains a column of __________ that are connected by muscles.

<p>ossicles</p> Signup and view all the answers

The __________ are internal to the outer plates that are within the dermis.

<p>ossicles</p> Signup and view all the answers

Their arms are very flexible; locomotion is by __________. There are two main methods.

<p>arm movement</p> Signup and view all the answers

The ends of the arms coil around rocks, seaweeds, or other objects and __________ the animal forwards; because of the snake-like movement of the arms when doing this, these animals are sometimes called serpent stars.

<p>pull</p> Signup and view all the answers

The central disc is held above the substrate by three of the arms and the other two arms are moved forwards in pairs and function as __________.

<p>legs</p> Signup and view all the answers

Study Notes

Echinoderms Overview

  • Echinoderms belong to the phylum Echinodermata, encompassing sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers, and related species.
  • All echinoderms are marine organisms.

Unique Features of Echinoderms

  • Possess a unique water-vascular system, exclusive to echinoderms, which facilitates movement and feeding.
  • The water-vascular system comprises a madreporite, canals, ampullae, and tube feet.

Skeletal Structure

  • Echinoderms have an endoskeleton embedded in the dermis, made of calcium carbonate ossicles.
  • Ossicles vary in shape, may or may not be fused, and are supported by connective tissue when not fused.
  • Fused ossicles create a rigid skeletal form in some species.

Symmetry and Nervous System

  • Adults display radial, biradial, or bilateral symmetry, depending on the species.
  • Lacking a brain, their nervous system consists of nerve rings from which nerves extend.

Respiratory and Circulatory Functions

  • Coelomic fluid, driven by ciliary action, aids in respiration and nutrient transport.
  • Oxygen and nutrients primarily move through coelomic fluid, with some assistance from blood.

Reproductive Traits

  • Most echinoderms are dioecious, with external fertilization being common.
  • The blastopore during embryonic development becomes the anus in echinoderms.

Larval Characteristics

  • Echinoderm larvae exhibit bilateral symmetry and are typically planktonic.
  • Larvae types include ciliated forms specific to each class.

Class-Specific Characteristics

Asteroidea (Sea Stars)

  • Characterized by arms that merge with a central disc.
  • Possess ambulacral grooves and tube feet used for locomotion and feeding.
  • Exhibit bipinnaria and brachiolaria larval stages.

Ophiuroidea (Brittle Stars)

  • Arms sharply distinct from the central disc; lack ambulacral grooves.
  • Have brittle and flexible arms, utilizing locomotion methods like coiling around objects for movement.
  • Their larval stage typically includes ophiopluteus.

Echinoidea (Sea Urchins, Sand Dollars)

  • Lack arms; their endoskeleton consists of fused plates.
  • Spines are highly maneuverable, facilitated by ball and socket joints.
  • Have an echinopluteus larval stage.

Holothuroidea (Sea Cucumbers)

  • Lack arms and spines; have elongated bodies.
  • Display auricularia and doliolaria larval stages during development.

Crinoidea (Crinoids)

  • Possess arms and ambulacral grooves but lack spines.
  • Include two main types: sea lilies and feather stars.
  • Larvae often undergo both doliolaria and auricularia stages.

Feeding and Digestion in Sea Stars

  • Primarily consume slow-moving prey, including bivalve mollusks, by eviscerating them with their stomachs.
  • Digestive enzymes dissolve prey into a thick broth, continuing digestion in the stomach and pyloric ceca.

Respiration and Excretion in Sea Stars

  • Respiration occurs through papulae and tube feet; ammonia diffuses out alongside carbon dioxide.
  • Pedicellariae function to keep the body surface clean of debris.

Regeneration and Autotomy

  • Sea stars can regenerate arms and undergo autotomy to escape predators, allowing for the potential recovery of full star from a detached arm containing part of the disc.

Conclusion

  • Echinoderms exhibit a variety of specialized structures and functions adapted to their marine environments, making them a diverse and fascinating group within the animal kingdom.

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Description

Test your knowledge about echinoderms including sea stars, sea urchins, and more. This quiz covers definitions and characteristics that define this unique group of marine animals. Perfect for students studying marine biology or anyone interested in ocean life!

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