Part 4 — Echinodermata, Hemichordata & Other Invertebrate Phyla (Q.76–100)

Part 4 — Echinodermata, Hemichordata & Other Invertebrate Phyla (Q.76–100)

Q76. Echinoderms display which symmetry in adult and larval stages respectively?

A) Bilateral in adult, radial in larva
B) Radial (pentaradial) adult; bilateral larva (pluteus/auricularia)
C) Asymmetry in both
D) Radial in both
Answer: B
Explanation:
A) Reverse.
B) Correct — echinoderm larvae are bilateral; adults show secondary radial symmetry.
C/D) Incorrect.

Q77. Water vascular system in echinoderms functions mainly in:

A) Feeding, locomotion and respiration using tube feet
B) Photosynthesis
C) Excretion of nitrogenous waste only
D) Digestion exclusively
Answer: A
Explanation:
A) Correct — tube feet and podia aid movement, feeding, gas exchange.
B–D) Not accurate.

Q78. Which class of echinoderms includes starfish?

A) Ophiuroidea
B) Asteroidea (sea stars / starfish)
C) Holothuroidea
D) Crinoidea
Answer: B
Explanation:
A) Brittle stars.
B) Correct — Asteroidea are starfish.
C) Sea cucumbers.
D) Sea lilies/feather stars.

Q79. Hemichordates (e.g., Balanoglossus) possess which chordate-like features?

A) Notochord and dorsal hollow nerve cord fully developed
B) Stomochord and gill slits; but lack true notochord — primitive chordate features
C) Jointed appendages
D) Exoskeleton
Answer: B
Explanation:
A) Not true; hemichordates have stomochord, not a true notochord.
B) Correct — possess pharyngeal gill slits and stomochord.
C/D) Not present.

Q80. Which is a defining feature of Echinodermata?

A) Presence of exoskeleton of calcareous ossicles and pentamerous radial symmetry in adults
B) Segmentation into metameres
C) Chitinous cuticle with moulting
D) Lungs for respiration
Answer: A
Explanation:
A) Correct — ossicles are calcified plates and pentaradial symmetry.
B) Segmentation — annelids.
C) Arthropod feature.
D) Not typical.

Q81. Echinoderms are deuterostomes like chordates because:

A) Blastopore becomes mouth
B) Blastopore becomes anus and radial cleavage is seen
C) They have jointed appendages
D) They are protostomes
Answer: B
Explanation:
A/D) Protostome traits.
B) Correct — deuterostome developmental pattern applies to echinoderms and chordates.
C) Not relevant.

Q82. A unique excretory product of marine echinoderms is:

A) Uric acid crystals like insects
B) Ammonia diffused into seawater (ammonotelic)
C) Urea stored in bladder
D) Solid nitrogenous waste only
Answer: B
Explanation:
A/C/D) Not typical.
B) Correct — echinoderms are ammonotelic; ammonia diffuses into surrounding seawater.

Q83. Which of the following are pinnate or feather-like larval forms in echinoderms?

A) Planula
B) Bipinnaria and pluteus larva forms are typical (bipinnaria in asteroids; pluteus in echinoids and ophiuroids)
C) Trochophore
D) Nauplius
Answer: B
Explanation:
A) Cnidarian larva.
B) Correct — bipinnaria, pluteus are echinoderm larvae.
C) Annelid/molluscan larva.
D) Crustacean larva.

Q84. Which of the following phyla includes filter-feeding colonial animals forming bryozoans?

A) Bryozoa (Ectoprocta) are colonial, mostly marine, filter-feeders using lophophore
B) Bryophyta
C) Porifera
D) Echinodermata
Answer: A
Explanation:
A) Correct — Bryozoa possess lophophores.
B) Plant phylum.
C/D) Different groups.

Q85. Brachiopoda superficially resemble bivalve molluscs but differ by:

A) Shell symmetry (dorsal-ventral valves vs lateral valves) and lophophore feeding organ
B) Jointed legs
C) Having radula
D) Presence of notochord
Answer: A
Explanation:
B/C/D) Not applicable.
A) Correct — brachiopods have different valve orientation and lophophore for feeding.

Q86. Which of these is true for Chaetognatha (arrow worms)?

A) They are segmented annelids
B) They are predatory marine worms with grasping spines and transparent bodies, important planktonic predators
C) They are freshwater filter feeders
D) They are echinoderms
Answer: B
Explanation:
A/C/D) Incorrect.
B) Correct — arrow worms (chaetognaths) are planktonic predators.

Q87. Which phylum contains animals with tube feet and ambulacral grooves?

A) Mollusca
B) Echinodermata
C) Arthropoda
D) Annelida
Answer: B
Explanation:
A/C/D) Not correct.
B) Correct — echinoderms like starfish have tube feet and ambulacral grooves.

Q88. Which invertebrate phylum shows a notochord-like structure called stomochord?

A) Hemichordata (e.g., Balanoglossus) — stomochord present but not true notochord
B) Echinodermata
C) Porifera
D) Cnidaria
Answer: A
Explanation:
A) Correct — stomochord is hallmark of hemichordates.
B–D) Not related.

Q89. Echinoderms possess which type of skeleton?

A) External chitinous skeleton
B) Endoskeleton of calcareous ossicles beneath epidermis
C) No skeleton at all
D) Exoskeleton of silica
Answer: B
Explanation:
A/D) Incorrect.
B) Correct — calcified endoskeleton in echinoderms consists of ossicles.

Q90. Larvae of which invertebrate group show trochophore larva?

A) Mollusca and Annelida commonly have trochophore larvae
B) Arthropoda exclusively
C) Cnidaria only
D) Echinodermata only
Answer: A
Explanation:
B–D) Not exclusive.
A) Correct — trochophore is characteristic of many annelids and molluscs.

Q91. Which of these is a sessile lophophorate?

A) Phoronida (and Bryozoa, Brachiopoda have lophophores)
B) Annelida
C) Arthropoda
D) Nematoda
Answer: A
Explanation:
A) Correct — phoronids are sessile filter feeders with lophophore.
B–D) Free-living/mobile.

Q92. The madreporite in echinoderms is:

A) Opening of digestive tract
B) Sieve-like plate connecting water vascular system to outside, regulating water entry
C) Respiratory organ
D) Sensory organ in arthropods
Answer: B
Explanation:
A/C/D) Incorrect.
B) Correct — madreporite connects water vascular system.

Q93. Hemichordates are important in evolutionary studies because they:

A) Are ancestral to fungi
B) Possess some chordate characters (pharyngeal slits) and thus help understand chordate origins
C) Have exoskeletons like arthropods
D) Lack any relation to chordates
Answer: B
Explanation:
A/C/D) Not true.
B) Correct — hemichordates show features bridging non-chordates and chordates.

Q94. Which of the following echinoderm classes include sea cucumbers?

A) Asteroidea
B) Holothuroidea (sea cucumbers) — soft-bodied with reduced ossicles and tube feet adapted for deposit feeding
C) Echinoidea
D) Ophiuroidea
Answer: B
Explanation:
A) Starfish.
B) Correct — sea cucumbers.
C) Sea urchins.
D) Brittle stars.

Q95. Which of the following is NOT true for echinoderms?

A) They have water vascular system
B) They show indeterminate radial cleavage and deuterostome development
C) Adults are bilaterally symmetrical
D) Tube feet are used for locomotion
Answer: C
Explanation:
A/B/D) True statements.
C) False — adults are radially (usually pentaradial) symmetrical; larvae are bilateral.

Q96. The ambulacral system in echinoderms is homologous to which system in chordates?

A) Not homologous to a specific chordate system, but represents a unique deuterostome innovation; some developmental genes show deep homology
B) Notochord
C) Dorsal nerve cord
D) Exoskeleton
Answer: A
Explanation:
B/C/D) Not homologous directly.
A) Correct — ambulacral system is unique but shows developmental genetic links across deuterostomes.

Q97. Which group has bilateral larvae and pentaradial adults?

A) Porifera
B) Echinodermata
C) Cnidaria
D) Arthropoda
Answer: B
Explanation:
A/C/D) Not applicable.
B) Correct — echinoderms.

Q98. Hemichordata and Echinodermata together with Chordata make up which clade?

A) Lophotrochozoa
B) Ecdysozoa
C) Deuterostomia (they are deuterostomes)
D) Protostomia
Answer: C
Explanation:
A/B/D) Incorrect.
C) Correct — these phyla are deuterostomes.

Q99. Which phylum includes filter-feeding, sessile marine animals with crown-like lophophore?

A) Mollusca
B) Bryozoa (Ectoprocta) and Brachiopoda possess lophophore — filter-feeding organ
C) Cnidaria
D) Arthropoda
Answer: B
Explanation:
A/C/D) Not lophophore-bearing.
B) Correct.

Q100. Tube feet in starfish are operated by:

A) Muscle contraction only
B) Hydraulic pressure of water vascular system controlled by madreporite and ampullae
C) Ciliary currents only
D) Tracheal system
Answer: B
Explanation:
A/C/D) Not accurate.
B) Correct — ampullae contract/relax to extend/retract tube feet via hydraulic pressure. (more…)