Lecture 9: The Deuterostomes Practice Flashcards

Fill-in-the-blank practice cards based on BIOL 3100 Lecture 9 covering Deuterostomes, Echinoderms, Hemichordates, and Chordates.

In deuterostome development, the cleavage pattern is __________.

Radial

A __________ embryo in deuterostomes means that an excised blastomere can still develop into a normal larva.

Regulative

The blastopore in deuterostomes develops into the __________.

Anus

In deuterostomes, the coelom forms through a process called __________, where it outpockets from the gut.

Enterocoely

A defining feature shared by deuterostomes is the presence of pharyngeal __________ slits.

Gill

Phylum __________ translates to ‘bristle mouth’ and is commonly called arrow worms.

Chaetognatha

Unlike typical deuterostomes, Chaetognaths exhibit __________ cleavage.

Spiral

Chaetognaths are planktonic predators that use grasping __________ on their heads to capture prey.

Spines

The organisms in Phylum Chaetognatha are __________, possessing both male and female reproductive organs.

Hermaphroditic

Phylum Chaetognatha lacks dedicated __________ or excretory systems.

Respiratory

Molecular dating suggests that protostomes and deuterostomes diverged in the Ediacaran period around __________ Mya.

$$600$$

Stem ambulacrarians and chordates first appear in the fossil record during the __________ period.

Cambrian

Phylum Echinodermata includes sea stars, brittlestars, crinoids, urchins, and __________.

Sea cucumbers

The name Echinodermata comes from the Greek words for ‘hedgehog’ and __________.

‘skin’

Echinoderms possess a hardened endoskeleton made of __________.

Ossicles

The __________ system in echinoderms is used for locomotion, feeding, and respiration.

Water-vascular

Echinoderms utilize __________ for gripping surfaces and locomotion.

Tube feet

Adult echinoderms typically exhibit __________ symmetry.

Pentaradial

Echinoderms generally have a very simple nervous system and no __________.

Brain

Primitive echinoderms had gill slits, but modern forms have __________ lost them.

Secondarily

The specialized meshwork structure of echinoderm endoskeletal plates is known as __________.

Stereom

Class __________ includes sea lilies and feather stars.

Crinoidea

Adult crinoids are mostly __________ and reside in marine deep-water environments.

Sessile

In crinoids, the arms possess __________ used for filter-feeding.

Pinnules

Limestone that is composed of more than $50\%$ crinoid remains is called __________.

Encrinites

Class Asteroidea, commonly called sea stars, are __________ predators of bivalves and corals.

Benthic

The __________ is the opening to the water vascular system located on the aboral surface of a sea star.

Madreporite

Sea stars move water from the madreporite into the __________ canal.

Stone

From the stone canal, water in a sea star flows into the __________ canal.

Ring

The tiny muscular clamps found on the surface of some echinoderms are called __________.

Pedicellariae

To digest prey, sea stars evert their __________ stomach.

Cardiac

The sea star species __________ was identified by Robert Paine as a keystone species.

Pisaster ochraceus

A __________ species has a large effect on its environment relative to its abundance.

Keystone

Class __________ includes brittlestars and basketstars.

Ophiuroidea

Unlike sea stars, Ophiuroids lack __________ and use gills for respiration.

Pedicellariae

In Ophiuroidea, the ambulacral grooves are __________.

Closed

The tube feet of brittlestars lack __________, unlike those of sea stars.

Suckers

In brittlestars, the site of digestion is the __________, as the cecum does not enter the arms.

Central disk

Class Echinoidea includes sea urchins and __________.

Sand dollars

The dermal ossicles of echinoids are fused to form a solid, rigid structure called a __________.

Test

Echinoids use moveable __________ for both locomotion and defense.

Spines

The specialized chewing mouth structure in sea urchins is called __________.

Aristotle's lantern

Sea urchin __________ are considered a delicacy in many places, including Japan.

Gonads

Class Holothuroidea consists of organisms commonly known as __________.

Sea cucumbers

Sea cucumbers are characterized by an elongated __________ axis.

Oral-aboral

In sea cucumbers, the dermal ossicles are __________ compared to other echinoderms.

Reduced

Sea cucumbers possess __________ that surround the mouth for feeding.

Oral tentacles

A __________ tree fans out from the cloaca in sea cucumbers to aid in gas exchange.

Respiratory

The defensive behavior of sea cucumbers expelling their internal organs is called __________.

Evisceration

The sea cucumber species __________ can grow to be over $2$ feet long.

Thelenota ananas

Small fish called __________ are known to live inside the anus of sea cucumbers.

Pearlfish

Phylum __________ consists of acorn worms.

Hemichordata

Hemichordates possess a large, retractable __________ that fits into a collar.

Proboscis

Hemichordates are mostly direct __________ feeders living in sediment.

Deposit

Like chordates, hemichordates possess __________ in their pharynx.

Gill slits

A __________ is a rigid, fluid-filled structure in a fibrous sheet found in all chordates.

Notochord

In chordates, the notochord is located below the __________.

CNS

The nerve cord in chordates is dorsal, hollow, and formed from the __________.

Ectoderm

Adult chordates typically have the dorsal nerve cord separated from the epidermis by __________ cells.

Neural crest

The __________ in lower chordates secretes mucus for trapping food.

Endostyle

In more derived chordates, the endostyle transforms into the __________ gland.

Thyroid

All chordates possess a muscular __________ tail at some stage of development.

Postanal

The earliest undisputed fossil chordate is __________, which lived approximately $500$ Mya.

Pikaia gracilens

Unlike most chordates, the fossil Pikaia gracilens possessed a __________.

Cuticle

Subphylum __________ includes the lancelets, which are fish-like marine filter feeders.

Cephalochordata

In Cephalochordates, the notochord extends to the __________.

Tip of the head

Cephalochordates create a ciliary current for feeding using a __________ organ.

Wheel

The segmented muscles found in Cephalochordates are called __________.

Myomeres

Cephalochordates have a circulatory system similar to vertebrates but lack a __________.

Heart

Cephalochordates lack several organs common in vertebrates, including gills, kidneys, and a __________.

Brain

Subphylum __________ includes sea squirts, salps, and larvaceans.

Urochordata

Urochordates are commonly referred to as __________.

Sea squirts or salps

Adult Urochordates generally lose most __________ features that were present in their larvae.

Chordate

Class __________ within Urochordata represents the sea squirts.

Ascidiacea

Class __________ includes colonial salps that drift in the open ocean.

Thaliacea

Salps move through the water using __________.

Jet propulsion

Class __________ contains larvaceans.

Appendicularia

Adult larvaceans retain a __________ appearance and build houses out of cellulose.

Tadpole-like

The larvacean house contains __________ filters to trap food particles.

Feeding

The tunic of a tunicate is made of a material similar to __________.

Cellulose

The muscular clamps found in Asteroidea are called __________.

Pedicellariae

In the water vascular system, water flows from the ring canal into __________ canals.

Lateral

In sea stars, the __________ serves as a sieve for the water vascular system.

Madreporite

Echinoderms have a __________ nervous system without a centralized brain.

Diffuse

The three major groups of Urochordates are Ascidiacea, Thaliacea, and __________.

Appendicularia

The __________ surface of a crinoid is used for attachment to the substratum.

Aboral

In Ophiuroidea, the madreporite is moved to the __________ surface.

Oral

Holothuroidea show an elongation of the ___________ axis.

Oral-aboral

In Asteroidea, the __________ grooves are open and contain tube feet.

Ambulacral

In Echinoidea, the ambulacral grooves are ___________.

Closed

The digestive system of an ascidiacean features an ___________ siphon for water intake.

Incurrent

The __________ siphon is where water exits the body of a tunicate.

Excurrent

Acorn worms belong to the Phylum __________.

Hemichordata

Hemichordates have a body divided into a proboscis, a __________, and a trunk.

Collar

The __________ of an acorn worm is used to filter blood-like fluid.

Glomerulus

The __________ nerve cord is a key chordate synapomorphy formed from ectoderm.

Dorsal hollow

Human embryos at $5$ weeks possess a ___________ tail.

Postanal

The endostyle secretes __________ to help trap food in lower chordates.

Mucous

In sea cucumbers, the madreporite is __________.

Internal

Deuterostomes and protostomes are both branches of the __________ family tree.

Metazoan