ZY2005 INVERTEBRATE DIVERSITY 2026
QUESTIONS AND CORRECT ANSWERS A+
ZOOLOGY STUDY GUIDE AND EXAM PREP
Name the classes of Porifera - CORRECT ANSWER-Calcarea,
Hexacactinellida, demospongiae and homoscleromorpha
How many living species of Porifera? - CORRECT ANSWER-8000
how does distribution effect Porifera shape? - CORRECT ANSWER-
usually incrusted asymmetrical shape in shallow forms, deeper forms are
larger and symmetrical, species in sedimentation are upright and tall to
avoid sedimentation
What are spicules and what are they made of? - CORRECT ANSWER-
skeletal structures in most sponges, made from silica or calcium
what skeletal structure may a sponge without spicules have? - CORRECT
ANSWER-may have a fibrous collagen network
name 2 sponges that are commercially exploited - CORRECT ANSWER-
Hippospongia and Spongia
,The class Sclerospongiae was split into what which 2 classes - CORRECT
ANSWER-demospongiae and calcarea
Class Homoscleromorpha - CORRECT ANSWER-can be encrusting,
simple, little variation in spicules or no spicules
How big is the class Demospongiae? - CORRECT ANSWER-85% of living
sponge species
Class Demospongiae - CORRECT ANSWER-"common sponges",spicules
either monaxons or tetraxons, spicules, collagen or no spicules
Class Calcarea - CORRECT ANSWER-calcium carbonate spicules, 1 3 and
4 rayed, asconoid synconoid or leuconoid
Class Hexactinellida - CORRECT ANSWER-"glass sponges",6 rayed
spicules, silica, syncytial, marine deep water species
what does syncytial mean? - CORRECT ANSWER-multinucleated mass of
cytoplasm as opposed to membranes dividing tissues
Name a type of Hexactinellida? - CORRECT ANSWER-Euplectella
, key characteristics of porifera? - CORRECT ANSWER-no true tissues or
organs, cells totipotent, choanocytes, sessile, suspension feeders, spicules in
some or collagen fibres
what kind of body system do porifera use? - CORRECT ANSWER-
aquiferous system to bring water in for feeding and gaseous exchange and
waste and reproductive elements out, pumped by choanocytes
spongocoel - CORRECT ANSWER-internal cavity of a sponge, lined with
choanocytes
osculum - CORRECT ANSWER-exhalent opening in sponge where water
leaves
ostia - CORRECT ANSWER-inhalent pores in a sponge where water enters
asconoid - CORRECT ANSWER-Simplest form of sponges, with canals
leading directly from the outside to the interior
syconoid - CORRECT ANSWER-folding of atrial chamber, ostia replaced
by dermal pores/incurrent canals
Leuconoid - CORRECT ANSWER-additional folding, no atrium, multiple
osculum with different diameters- different water flow rates, all
demospongiae
QUESTIONS AND CORRECT ANSWERS A+
ZOOLOGY STUDY GUIDE AND EXAM PREP
Name the classes of Porifera - CORRECT ANSWER-Calcarea,
Hexacactinellida, demospongiae and homoscleromorpha
How many living species of Porifera? - CORRECT ANSWER-8000
how does distribution effect Porifera shape? - CORRECT ANSWER-
usually incrusted asymmetrical shape in shallow forms, deeper forms are
larger and symmetrical, species in sedimentation are upright and tall to
avoid sedimentation
What are spicules and what are they made of? - CORRECT ANSWER-
skeletal structures in most sponges, made from silica or calcium
what skeletal structure may a sponge without spicules have? - CORRECT
ANSWER-may have a fibrous collagen network
name 2 sponges that are commercially exploited - CORRECT ANSWER-
Hippospongia and Spongia
,The class Sclerospongiae was split into what which 2 classes - CORRECT
ANSWER-demospongiae and calcarea
Class Homoscleromorpha - CORRECT ANSWER-can be encrusting,
simple, little variation in spicules or no spicules
How big is the class Demospongiae? - CORRECT ANSWER-85% of living
sponge species
Class Demospongiae - CORRECT ANSWER-"common sponges",spicules
either monaxons or tetraxons, spicules, collagen or no spicules
Class Calcarea - CORRECT ANSWER-calcium carbonate spicules, 1 3 and
4 rayed, asconoid synconoid or leuconoid
Class Hexactinellida - CORRECT ANSWER-"glass sponges",6 rayed
spicules, silica, syncytial, marine deep water species
what does syncytial mean? - CORRECT ANSWER-multinucleated mass of
cytoplasm as opposed to membranes dividing tissues
Name a type of Hexactinellida? - CORRECT ANSWER-Euplectella
, key characteristics of porifera? - CORRECT ANSWER-no true tissues or
organs, cells totipotent, choanocytes, sessile, suspension feeders, spicules in
some or collagen fibres
what kind of body system do porifera use? - CORRECT ANSWER-
aquiferous system to bring water in for feeding and gaseous exchange and
waste and reproductive elements out, pumped by choanocytes
spongocoel - CORRECT ANSWER-internal cavity of a sponge, lined with
choanocytes
osculum - CORRECT ANSWER-exhalent opening in sponge where water
leaves
ostia - CORRECT ANSWER-inhalent pores in a sponge where water enters
asconoid - CORRECT ANSWER-Simplest form of sponges, with canals
leading directly from the outside to the interior
syconoid - CORRECT ANSWER-folding of atrial chamber, ostia replaced
by dermal pores/incurrent canals
Leuconoid - CORRECT ANSWER-additional folding, no atrium, multiple
osculum with different diameters- different water flow rates, all
demospongiae
