1. Life cycle and breeding of squids

2. Introduction Phylum-molluscs Most advanced group.
800sp have been recorded.
Most interesting group because of their behaviour patterns.
Exclusively marine.
Intro…....
Phylum-molluscs
Bilaterally symmetrical.
Interesting group because of their behaviour patterns they exhibit.
Exclusively marine.

3. Morphology of squid Bilaterally symmetrical. Oval shaped body.
Body –divided into head and trunk.
Internal shell (gladius) is present.
8 sessile arms and 2 tentacular arms.
Fin lobes fused posteriorly.
Locomotin – jet of water produced by ventral siphon.

4. Morphology
Morphology

5. Distribution & Habitat
World wide distribution in warm waters
Abundant in the Indian seas.
But they are in great shoals in Gulf of Kutch, Gulf of Mannar and Palk Bay.
It is found mostly in the deep waters.
Distribution & Habitat
Genus Loligo has a world wide distribution in warmer seas.
Squids r quite abundant in the indian coastal waters.
But they r hunt in t great shoals in great shoals in inland waters-Gulf of Kutch.Gulf of Mannar and Palk Bay.

6. Breeds mainly in the spring and in the early summer.
It can move fast both back and front by funnel
It uses a black ink to escape from the predators.
Has a great power of rapid colour change.
Breeds mainly in the spring and in the early summer.
It can move fastly both back and front by funnel
It uses a black ink to escape from the predators.
Integument has a great power of rapid colour change.

7. Stage I Stage II Stage III Stage IV Stage V L.forbesi Male Female
Testis transparent and appears as an enlargement of the genital aorta.
Ovary transparent and membranous, oviduct and oviductal gland appear.
Stage II
Testis translucent and soft, spermatophoric organ translucent .vas deferens transparent & not visible.
Ovary translucent & fluffy, oviduct and oviducal gland translucent, nidamental glands opaque.
Stage III
Testis extends to posterior apex of mantle ,vas deferens full of sperm & creamy white, arm clearly visible
Ovary with eggs visible; oviductal gland opaque; oviduct large and transparent
Stage IV
Testis extends anteriorly past post tip of stomach, spermatophoric sac packed with spermatophores
Ovary with eggs of different sizes, oviductal gland creamy white ; nidamental gland exude viscous fluid with cut.
Stage V
As stage IV, but with spermatophores in distal vas deferens and penis.
As stage IV, but with eggs in distal oviduct.

8. Reproductive system Sexes are separate. Single testis.
A single gland of the visceral mass opens directly into the coelom by slit.
Gonoduct runs on the left from the coelom to the mantle cavity & opens near funnel.
Hectocotylized arm – copulatory organ
It is used for the transfer of sperm.
Reproductive system
Sexes are separate.
A single gland of the visceral mass opens directly into the coelom by slit.
Gonoduct runs on the left from the coelom to the mantle cavity & opens near funnel.
Hectocotylized arm is present for transfer of sperm.

9. Male
It includes a testis, a vas deferens, a spermatophoric sac containing sperm packets & a copulatory organ or penis.
Female
It comprises of an ovary, an oviductal gland, and a part of nidamental glands, which produce a jelly in which the eggs are embedded.
It comprises of an ovary, an oviducal gland, and a part of nidamental glands, which produce a jelly in which the eggs are embedded.

10. Sexual dimorphism Male Female 3.Hooks absent.
1.Gonoducts single
2.Suckers on buccal lappets.
3.Hooks present in tentacular club.
Female
1.Gonoducts paired
2.Suckers absent
3.Hooks absent.
Suckers on buccal lappets

11. Tentacular club
suckers
Tetacular club

12. during mating.. attracting females begins in the morning
Around dawn swims rapidly in very large circles
After some time the squids they start swimming in pairs.
These r mating couples.
Males start changing colours to attract female.
Once the female shows interest mating takes place.
Before copulation
The process of attracting females begins in the mornings. Around dawn they can be seen swimming rapidly in very large circles.
The females join in this swim in circles which initially can seem very strange and out of control. However, as time goes by you will start to notice that these squid are now swimming in pairs as they go around. These are the couples that have linked up for mating to take place. The males have changing colors on them which is what attracts the females to them. Once a female has shown an interest the mating takes place.

13. The females have an ink sac under a set of glands in gills.
During mating ,sperms are stored inside sac where they will fertilize her eggs.
Male uses the shorter arm to place the sperm.
Female uses the nidamental secretion to stick the eggs in the solid object in the event.
7-8 weeks to hatch out.
The females have an ink sac under a set of glands in the gills.
During mating the sperms are stored inside the sac where they will fertilize her eggs.
Male uses the shorter arm to place the sperm.
Female uses the nidamental secretion to stick the eggs in the solid object in the environment.

14. Life cycle…. Within 1-2 years.
Universal pattern-that coleoidea are single breeding & short life span.
Life cycle characteristics is based on relatively small no of species; that occur in the shelf and coastally based scientific study.
Similar for squid, octopus, cuttlefish.
Life cycle….
Universal pattern-that coleoidea r single breeding & short life span.
Life cycle characteristics is based on relatively small no of species; that occur in the shelf and coastally based scientific study.

15. Life cycle of squid
Life cycle of squid

16. Single breeding Semelparous
All cephalopods undergo only one breeding cycle(monocycly), except nautiluses.
Semelparous
All the modern cephalopods are single-season breeders
Single breeding (semelparous)
All cephalopods undergo only one breeding cycle(monocycly), except nautiluses.
All the modern cephalopods are single-season breeders in the strict sense.
The term semelparity was first proposed by l.c.cole to describe the condition of multiplying only once in a life time.

17. The term semelparity was first proposed by L. C
The term semelparity was first proposed by L.C.Cole to describe the condition of multiplying only once in a life time.
Cephalopods have a clearly defined breeding event, followed by death.