Chordata/Fish

Tunicates

________ have an endostyle, which is a glandular tissue that runs along the length of the pharynx.

Viviparous elasmobranchs

________ retain the developing embryo inside the female's body during gestation.

Agnathans

________ are divided into two major groups: hagfishes (Myxini) and lampreys (Petromyzontida)

circulatory system

The hagfish's ________ is simpler than that of other vertebrates.

Hagfish play

________ a vital role in the marine ecosystem by scavenging dead or dying organisms, which helps to recycle nutrients.

Cephalochordates

________ also possess a hollow, dorsal nerve cord that runs along the length of their body.

Actinopterygii

________ is divided into two subclasses: Chondrostei and Neopterygii.

flexible rod

This is a(n) ________ that runs parallel to the nerve cord and provides support and stiffness to the body.

ampullary organs of Lorenzini

The ________ are an essential adaptation for cartilaginous fish, which have poor vision and rely on other senses to navigate through their environment.

Actinopterygii

________ includes a wide range of feeding strategies.

Phylum Chordata

Notochord: One of the most important characteristics of the ________ is the presence of a notochord.

Craniata

________ is a subphylum of chordates that includes all animals that have a cranium or skull.

complex nervous system

The Craniata also have a well- defined and ________ that allows them to respond to environmental stimuli in a much more sophisticated manner than the invertebrate counterparts.

Gnathostomata

________ are vertebrates with jaws, and they are the most advanced animals among the chordates.

important ecological role

They play a(n) ________ in marine ecosystems by filtering seawater and exchanging nutrients and gases with the surrounding environment.

Fertilization

________ occurs when sperm from the male is deposited into the female's oviduct and ________ the egg (s)

pharynx

The ________ is a muscular tube that extends from the mouth and into the body.

notochord

In vertebrates (animals with a backbone), the ________ is replaced by the spine during development.

central processing

The skull or cranium protects the brain, which is the ________ center in these animals.

respiratory pigment

They have only one heart, and lack a(n) ________ such as hemoglobin.

Urochordates

________ also have potential applications in the biomedical field, where their unique cellulose tunics have been used in developing tissue- engineering scaffolds and drug- delivery systems.

sea lamprey

Stage 2: Larva Once the eggs hatch, the ________ enters the larval stage of its life cycle.

nerve cord

In addition to the ________, they have a number of sensory structures, including tentacles, photoreceptor cells, and a specialized balancing organ called a statocyst.

main types of reproduction

There are two ________ in elasmobranchs- oviparity and viviparity.

unique body structure

They are characterized by a(n) ________ consisting of a tunic, or outer covering, made of tough cellulose material.

Chondrichthyes

________ have a unique type of scale known as placoid scales or dermal denticles.

Gnathostomes

________ have jaws formed from paired and modified gill arches, which played a critical role in their evolutionary success by allowing them to obtain and process food more effectively, which was arguably a key adaptation leading to radiation and diversification.

absence of jaws

The name Agnatha comes from the ________ in these fish.

Subphylum Cephalochordata

________ is a group of marine invertebrates that represents the most basal lineage of chordates.

Endostyle

________ or Thyroid gland: The ________ is a gland that runs along the bottom of the pharynx and is thought to play a role in the production of mucus or hormones.

Post anal tail

________: Finally, all chordates have a(n) ________, which is an extension of the body that lies beyond the anus.

Chondrostei

________ includes the sturgeons and paddlefish, while Neopterygii includes all other ray- finned fish.

Phylum Urochordata

________, commonly known as tunicates or sea squirts, is a group of marine invertebrates that belong to the subphylum Tunicata.

marine

They are small, ________, and invertebrate animals that have a few chordate features.

aquatic environments

They can be found in nearly all ________, including freshwater, saltwater, and brackish water.

planktonic organisms

It feeds on ________, and it is a filter feeder.

Hagfish

________ have a unique body structure that sets them apart from other fish.

cartilaginous skull

They have a(n) ________ and a simple, unpaired nostril for detecting odors.

primitive jawless fish

Hagfish, also known as slime eels, are ________ that belong to the class Myxini of the subphylum Vertebrata.

Agnatha

________ is a superclass of animals within the phylum Chordata that are jawless fish.

visual acuity

Additionally, gnathostomes have enlarged forebrains, cerebellums, and optic lobes that are more advanced than those of their jawless relatives, providing them with better spatial perception, memory functions, and ________.

Hagfishes

________ are unique in possessing a skull but lacking a vertebral column, while lampreys possess both a skull and a vertebral column.

Juvenile lampreys

________ feed on small fish and invertebrates, and their bodies become more streamlined and eel- like as they prepare for their migration to the ocean.

Protochordate

________ is a subphylum within the phylum Chordata.

evolution of jaws

The ________ and the paired limbs have contributed to the success of the Gnathostomata in dominating the planet.

respiratory system of Chondrichthyes

The ________ is unusual because they have five to seven pairs of gill slits that allow water to pass over their gills.

Ray

________- finned fish includes some of the most well- known and commonly consumed fish such as salmon, trout, tuna, and tilapia.

Oviparous elasmobranchs

________ lay egg cases that are fertilized internally and then deposited in the environment, either attached to substrate or left to float freely.

cylindrical body

They have a(n) ________ with no scales and a cartilaginous skeleton.

complex respiratory system

The gills of class actinopterygii are a(n) ________ that performs the crucial process of gas exchange, providing oxygen for cellular respiration and releasing carbon dioxide.

Notochord

One of the most important characteristics of the Phylum Chordata is the presence of a notochord

Dorsal nerve cord

Another defining characteristic of the Phylum Chordata is the presence of a dorsal nerve cord

Pharyngeal slits

The pharyngeal slits are a series of openings that are located in the pharynx (the part of the digestive tract between the mouth and esophagus)

Endostyle or Thyroid gland

The endostyle is a gland that runs along the bottom of the pharynx and is thought to play a role in the production of mucus or hormones

Post-anal tail

Finally, all chordates have a post-anal tail, which is an extension of the body that lies beyond the anus

There are two distinct body types within this phylum

solitary and colonial

The body of a tunicate is made up of three main parts

the siphons, the pharynx, and the endostyle

Cephalochordates are characterized by having a flexible, fish-like body plan that is divided into three distinct regions

the anterior, middle, and posterior regions

Agnathans are divided into two major groups

hagfishes (Myxini) and lampreys (Petromyzontida)

Stage 1

Egg The sea lamprey life cycle begins when a mature female lays her eggs in freshwater streams or rivers

Stage 2

Larva Once the eggs hatch, the sea lamprey enters the larval stage of its life cycle

Stage 3

Juvenile After several years, the sea lamprey larvae undergo metamorphosis, transforming into juvenile sea lampreys

Stage 4

Adult Once the sea lamprey reaches adulthood, it will migrate to the ocean where it will spend most of its life

Stage 5

Spawning When the adult sea lampreys reach sexual maturity, usually around five to seven years of age, they will return to freshwater streams or rivers to spawn

There are two main types of reproduction in elasmobranchs

oviparity and viviparity

Actinopterygii is divided into two subclasses

Chondrostei and Neopterygii